Capcom didn't make Street Fighter IV with the intention to stick with the Street Fighter III community, they made it to try to recapture the audience that was at the arcades playing Street Fighter II. They realized they may have made Street Fighter III lean too much towards the hardcore audience so they tried to tone it down a bit. I haven't tried the game myself but from everything I heard Street Fighter IV should be a great game.
Really, the original arcade roster for SFIV was the non-Super Turbo SFII cast and four new characters (Abel/Viper/Rufus/Furte), and at least two members of the new challengers from Super Turbo (Cammy/Fei Long) will make it into the home version. This game is really catering much more to the SFII fans and doesn't even seem to really care about SFIII. At the very least, I hope Dudley makes it into the game. Because he's rich.
