I've thought about this idea for some time now, and I wanted to show it for someone.
Basically, what I think Valve should do, is make a small devision devoted to updating older games that other companies have allowed them to mess around with.
This would be some kind of dream project for most of us, and even though I know it will most likely stay a dream, there are a couple of reasons why this could work.
1. Making even more money on older games
If older games would be updated with higher resolutions, achievements and Steam Cloud stuff, people would have a reason to want to play through the game again. I'm still waiting for my HL2 achievements, and if we get them, I would play through it just for the achievements.
2. Older games might survive tomorrow
I don't know, I think the people at Valve like games as much as anyone does, and this thought alone would make updating older games worthwhile. Though I don't know if stuff like making games 64-bit would be easy to do at all, or worthwhile even. Just a thought.
3. Steam would be even more appealing for new users
Steam would become even more accessable to new users, because of these older games. Steam would grow and grow and it might evolve in the process to something more.. I think.
I hope that someday, the Steam Store will become something like Amazon became. Shop from different vendors but in the same program, or something.
But how would you get money for the projects?
Remember Gabe's idea of player-funded games? I think this could work for these kinds of projects, but with a catch. You get to vote on which game gets threated, but with MONEY. In the end, most games would be updated but you just vote on which order they get updated in. Oh, and in the end, you would get a copy of the game to your Steam account.
Sorry if this was painful for any of you to read, but I don't really know how to express my idea any better.