This is all speculation - none of these games have come out, and we have no solid information.
MGS4 gameplay footage seems to be suffering from a 'Yahtzee's nightmares'-esque ailment that can only be called "stealth-to-warfare syndrome". A lot of the game has Snake stealthing and using the Metal Gear REX, but is equally filled, from what the E3 demo shows, with a large amount of warfare in the traditional war game style, if not Metal Gear Solidified somewhat.
Half Life 2: Episode 3 is not going to come out this year. Valve have spent months on the last 'Meet the Team' sketch, and it's concrete that EP3 will have to wait as long as 2010, god forbid. Valve is murderously slow, and I think before releasing a new title they'd like to shine the already-blinding TF2. Flooding the market with games adhering to Valve's high standards at the same time will only raise expectations and hype, therefore ruining their next few titles.
Killzone 2 is hyped, yes, but there is no telling what a game like that can get to - it looks like another COD4, loved by repetetive FPS fans and hated by people who wanted something different. It's a lot like Crysis, in the sense that the fans and critics aren't going to play it the way the developer intended. Run'n'gun mindsets ruined Crysis, and people really just avoided the nanosuit as opposed to utilizing it.
Spore cannot be overhyped in the sense that we've seen nothing like it before. It's too different to be hyped, it's not the killer of anything, it's the creation of a new genre. I guess some hype is classifying it as the RTS/Sims killer, but there's no telling what it's going to be like because we don't have any precedents with games on this scale and idea. I personally do not see anything in Spore that interests me.
The new Final Fantasy will be an improvement on the last, as all Final Fantasy games are, but again nothing groundbreaking. The series should have quit while it was ahead. I'm not saying I hate the entire series, it's just that the bare frame beneath the glossy sparkle, overhype, rabid fans and quaint Japanese 'normality', which we would call 'ridiculous' is starting to show and Square Enix is doing extremely well in using the same format to make different games.
Finally, SSBB depends entirely on whether Nintendo is trying to make the SSBM lightning strike again, or initiate new users into a decidedly - and embeddedly - gimmicky format. I don't know any details of the new game, I don't have a next-gen console (though I'm considering a PS3) and the PC is my main gaming output, yet I still love it. SSBB may be overhyped, it could just be gimmicky, or it could be groundbreaking. We'll leave that for the critics and playtesters to hype, and the actual market to confirm/deny.