Most ppl have already done Vice City too..and yeah I agree it's mostly kids now playing. If anything is "yesterday's news" it's VC. I mean the mainstream media can help you..but after too much exposure (just like Ben & Jen Lopez) it can hurt you. Believe me the GTA series will run it's course soon. And I'll bet it does'nt have the longevity of Mario.
I disagree about GTA, I think rockstar may be able to innovate enough that the series doesn't become old. Of course, if they just release the same thing every year...well, it works for sports games. But the idea behind GTA will eventually give way to something new, perhaps even more 'adult' than gta was.(unless mainstream culture has a sudden turn around)
BTW, I'm pretty sure last gen nintendo's best sellers were goldeneye, mario, and zelda ocarina of time, but I suppose mario kart could be 2nd.(if you ignore goldeneye...)
Also, if fzero gx is anything like fzero x, I expect you will see the cars reach 'over 3000 km'(doesn't mean that'll be fast compared to wipeout, I've only played extreme g3 on the current gen of systems, and while it may be fast, it is nowhere near as fluid as fzero) and it will have extremely narrow courses at points, about a vehicle and a half length.
Anyhow, I've always preferred fzero to wipeout because wipeout has always seemed sluggish to me, the weapons lame, the vehicles lame(not that fzero x's vehicles were so good), the courses simple, the music bad, and the game just generally unfun, the computer players were no fun to race and the multiplayer was very much akin to extreme g3 where you never see anyone else. Though, the only real thing I felt fzero x had over wipeout was solid gameplay(speed didn't seem too fast most of the time, speed really doesn't come into notice until you realize you're not going to make that turn or you have walls closing in on you), but that's what made it fun.