Bunny Hopping is always going to be there, as long as people think it makes you harder to hit, tbh most of the people playing UT2k4 find it easier to hit Bunny Hoppers, it just makes you laugh on voice comms, because of all the different tricks / jumps / boosts they have to use, they pick the Bunny Hopping.
The difference in skill won't be too bad, there's always ladders and cups for the highly skilled people out there, and you'll always find a l337 player pwning n00bs, but they normally get bored and look elsewhere for their fun. Also there's the pickup channels if you want a high skilled game, everyone who's played any game long enough, know where to go for an easy match or complete pounding. Tje newer people will soon learn, and hopefully it won't put them off the game. They just have to remember than when a new game comes out, everyone is a n00b, (until you've played it solidly for 4 days straight

). With a bit of luck they won't delay it for much longer. I reckon they should bring out a no vehicles game with just TDM and CTF now, and when they've finished fiddling with all the vehicles either put out a massive patch or an add on pack.