Well here's my list, some of the things maybe be the same as you said so I apologize for any re-stating what's been said:
1. Stick with the Blu-ray. By 2011 or 2012 when a PS4 comes out the costs of producing Blu-ray should be much much lower so this could make the PS4 quite inexpensive. They should launch the PS4 at no more then $299.
2. Make it powerful enough to run games fairly easily at 1080p with 60 frames per second. This would make the games look beautiful and run smoothly.
3. Online gaming should be a top priority right out of the gates. Put a fee on PSN if you have to, just make it good! I'd be willing to pay the $50 a year or whatever they would charge as long as its good.
4. Full internet browser with all the plug-ins and shit necessary to watch online videos and such. That would be amazing if the PS4 had internet good enough to basically function as a Personal Computer.
5. Also just an aesthetics thing here but the PS4 should be no bigger then the current PS3 slim. I mean the PS3 was fucking ugly before the re-design. Yeah the glossy finish looked nice but the thing weighed like 12 pounds or something, I could barely fit it in my suitcase to take it up to my cottage in the summer.
6. Huge hard drives and the ability to download PS1, PS2 and even PS3 games directly to our PS4's from the PSN. That would be amazing!
7. Please Sony do whatever it takes so that there are no mandatory installs for games. That is one of the most annoying things about the PS3. You buy a new game and you can't wait to get home and pop that sucker in and...oh, I've gotta install 5 gigabyte of game data before I can play. That sucks. Optional installs should be available to cut down on load times but please no mandatory ones.
8. This point has nothing to do with features but...I would guarantee Sony a 1st place start to the next generation if they have a same day (or at least same week) worldwide launch with a $299 price tag (and whatever that converts to in Euros and Yen) and a launch lineup consisting of at least a handful of worthwhile games to play. That would be epic.
Edit: 9. How silly of me to forget backwards compatibility with Playstation 3, Playstation 2 and Playstation games. That would be fly. Then if for some reason they decide not to have a good launch lineup then at least we can play Killzone 3 (which will be a PS3 game) on our Playstation 4's.
