Clearly Skyrim was very successful. And clearly game devs like copying past successful games. But there really isn't anything else like the Elder Scrolls and its mod encouraging design.

Now that Microsoft own Bethesda I'm very skeptical about ES6 being kept as it was in the past. I would not be surprised if it becomes exclusive to some sort of Microsoft online services. I'd also be surprised if it was kept single player.

Now seems like an opportunity for another company to insert themselves as the replacement. Certainly a game of that scope is a massive undertaking. Maybe akin to an offline MMO. But there are developers capable of it. And if nothing else there's plenty of room to improve combat compared to what Bethesda does.

I just find it odd no one has really tried to make another game of this type and fill that space recently.

Define "Skyrim-like game". I'm sure you can find many features in other games, but if you're asking for "60% like a Bethesda game" then, well, how many Dark Messiah of Might & Magic-likes are there? How many Battlefield 2142-likes are there? Just because Skyrim sold a bunch doesn't mean AAA publishers are going to redevelop their pipeline just to have an open world with multiple races and the ability to collect and throw garbage wherever you want. Maybe wait for Avowed to show more skin.

By "Skyrim-like, "do you mean very very very mod friendly? Because that's literally the only good thing about Skyrim and/or any other Bethesda-made game.

If that's the question, then yes I do find it odd that Bethesda is the only game maker who embraces mod makers so heavily, and indeed other game makers are behaving very strangely by giving Bethesda an unchallenged market monopoly over that concept, for no apparent reason.

Also:
The Wayward Realms
Wyrdsong

Heard very good things of the two premium total conversions that were released on GoG just recently, too:
Nehrim: At Fate's Edge
Enderal: Forgotten Stories

Basically yes. Modding was obviously a core feature of its design and a major reason for its longevity & commercial success.

Established developers generally stick with what is profitable and what they are comfortable making.

Elder Scrolls games have a lot of moving parts....characters with their own routines and behaviors, objects and environments to make the world feel alive, physics, combat, character creation, etc....all of this on a large scale to boot. Bethesda as developers, have many years of experience making those kinds of games. Other development teams that don't have previous experience on these types of games are taking a big risk, especially if they already have their own cash cows.

Oh, I think Rockstar could do it, and do it better than Bethesda.

Yeah, but Beth played their hand when they felt they could profit off mod makers' works. Their Creation kit started to include language that Beth owns the exclusive rights to anything you create with it, and then they decided to try and force the Creation Club, where they made 80% of the proceeds from every mod sold. It was a pathetic attempt to steal the community's ideas, and thankfully most people weren't having it.

But they (and also Bethseda-made Fallout games) also have a whole lot of copy & pasting. So that endless copy & pasting surely saves them tons of time and money with not them having to bother actually to put any real development effort into huge swathes of their games.

So that makes their accomplishments in other aspects of their games probably not-so-hard as they would otherwise be had they fully-developed every section of all of their games by hand.

And it should also be something that other copy & paste-happy devs could replicate.

When you are a fairly hardcore single player RPG and you sell 30 million copies you are doing more than a few things right. It's a fine game given its scope & original release date. It's nothing groundbreaking in 2023 but no one should expect it to be.

If you mean "given that Morrowind (2002) -> Oblivion (2006) -> Skyrim (2011) were released 4-5 years apart then where is long overdue Elder Scrolls 6 (2016) / Elder Scrolls 7 (2021)?", sadly Bethesda have figured out that reselling the same game over & over + charging people for free bug fixes that other people have made for them for free (Creation Club) is a more lucrative gravy train...

As for other studios replicating the experience, Elder Scrolls is really a unique combination of bugs + 'quirky jank gameplay' combined with extensive modding + epic Jeremy Soule soundtrack that overcomes the former issues that makes wandering about an Elder Scrolls world enjoyable. A lot of studios just don't have as 'open' an engine, ie, making a Skyrim like game in Unity / Unreal wouldn't really produce a Skyrim feeling like game if you couldn't mod it. So a studio would have to be competent enough to make their own engine too. Not only are there not many around (even EA cheaped out by trying to shoehorn Dragon Age Inquisition into a Frostbite engine clearly made for FPS's), deep down I get the feeling modern Bethesda is like modern Bioware - essentially 'coasting along' on past success with many staff who were previously competent enough to code RPG game engines from scratch having left the company / retired. Even Starfield uses Creation Engine 2 which may well just be the same as Creation Engine 1 under the hood with a lick of 4k RTX paint over the top.

I read that game developers / publishers are very protective of their intellectual property, often copyrighting everything they invent during the development process so that NO ONE ELSE could benefit with simply cloning the game mechanics but with better graphics.
After Max Payne game I expected to see many games with "bullet time" in them and I think I saw only 2 or 3 games with it, and a a few with time stopping / slowing function. Then later I read that that Bullet Time is a registered trademark owned by Warner Bros. Entertainment, Inc.

Monolith / Warner Bros. for example copyrighted "Nemesis" system for AI vengeful enemies used in their 2 games in Lords of the Rings setting. That mechanic is quite interesting and we might never see anything quite like that in our gaming life, how fun.

Given Bethesda's reputation, it wouldn't be surprising if they have also copyrighted every aspect of their special gaming approach, including trees, bushes, and technology, to protect their precious TES series. Additionally, they once threatened to sue Markus "Notch" Persson, the ex-owner of Mojang, for using the word "Scrolls" in their next game.

Here are some ridicilious examples you may read for yourself:
https://www.cbr.com/dumbest-video-game-copyright-claims/#video-game-insanity

And to answer your question:
Enderal: Forgotten Stories
https://www.gog.com/en/game/enderal_forgotten_stories

Enderal: Forgotten Stories is a total conversion for TES V: Skyrim: a game modification that is set in its own world with its own landscape, lore and story. It offers an immersive open world, all for the player to explore, overhauled skill systems and gameplay mechanics and a dark, psychological storyline with believable characters.

I think it's more than that. I bet there is some fear about making a new one that can top their prior success. A lot has happened since Skyrim came out. And a lot will be expected of a new entry. A big open world has been done numerous times at this point and combat in such games has gotten way better than anything in Skyrim. To make a new ES that surpasses modded Skyrim and holds up to things like Elden Ring, Witcher, Red Dead, GTA etc is going to be daunting.

I believe Baldur's Gate 3 will have been in development 6 or 7 years by the time it comes out. I can't see ES6 being done any faster & they need to finish Starfield 1st. And who knows what Microsoft's plans are for the franchise. So I don't see it happening any time soon.

Yeah, that might be cool, but that's still a Skyrim mod. What I'm hoping to see is a newer more advanced RPG that could be similarly modded & replace Skyrim.

Bethesda is largely surfing on it's name and due to past games. I mean, even though I didn't play the two first games, I do recognize them as ground-breaking and unique considering there weren't many games out there in the 90's, at least not in that type and size.

Naturally they harvested more on that success.

Fascinating enough, the bigger the studio got the bigger but simpler the games became... so yeah, I welcome anyone trying to replicate that success with huge mod support. However, people wouldn't play or let alone mod a game if the base game was completely awful.

I hope they up the notch in Starfield, and I also hope AVOWED is better than OW1, which was largely a mixed bag.

Relevant:
Why is There no Other Game Like Skyrim?
7 New Games to Play If You Love Skyrim 2023

So I guess Skyrims world, characters and lore is still in Enderal, right? ;P

Seriously, I see what you mean. But again, due to the sheer amount of games today I doubt it, at least in the same scope/type/atmosphere as Skyrim.