Let's paint the devil on the wall and say Valve shuts down Steam for whatever reason. What happens next?

Right. Someone else is buying the freakin' thing. Be it Microsoft, Sony, EA, CDRed or a conglomerate of gamers via kickstarter....
Your point is?

They won't sell well In those cases where there is a lot of uncertainty. Not until they catch on. There will be some that will pay for them and regret it, but that's always been the case and always will be.

It's not going to bring the market crashing down like it did in the 80s when people were buying them off of the shelves with none of the advantages of information access that we have today. By and large shovelware fails today because people know better.
It will be competitive, but I view that overall as a good thing for the consumers.

Couldn't care less if they die, as long as they give their customers what they paid for.

Is this one of those threads like I seen in the 7th guest forum that said "Omg, steams gonna die, this game is old!"

What's so bad about Steam dying anyway?

Don't you have a full backlog?
Something else will fill in the gap almost instantly, let's hope it's neither google's playstore nor facebook but gog.
Gaming is slowly but steadily growing into an acceptable past - time activity, you can't simply wipe that out only because Steam is going bananas.

Most of Steam's services aren't really integral to gameplay, so it's usually not going to be a huge issue if they don't work. The exception is of course games using Steam (only) for multiplayer, as we've seen with games using GameSpy. That's why games should always have more than one multiplayer option in my opinion.

Of course, if Steam does go down it'll be a major pain, just like with GOG for those of us who have lots of games here, but I don't think there will be a problem with the basic issue of playing games if you've got them (and hopefully installing them using the backup system). It's not like every single game needs to be patched, as they work offline already.

I hope it dies or removes its DRM.

My apologies, I now see that you meant that paranoid or greedy developers will find Steam conductive to their need as opposed to all developers releasing on Steam being paranoid or greedy.

Your statement left open many possible interpretations and I interpreted it in the world possible way.

...or EA, or Activision, or Ubisoft...

On the matter of the garbage Steam is piling on, it'd be nice to have a button (similar to the wishlist button) saying "Never show the current user this game again". That way, you could clear the crap away as you go.

Not perfect, of course, but better than the current situation.