I'm thoroughly opposed to any notions of making D&D into some kind of skill/feat-based point-buy system. Take away the classes, or render them largely unimportant, and you're killing D&D and reanimating its corpse as some Generic Overcomplicated Munchkin Point-Buy L33T Fantasy Wargame: D34TH 2 N3WB$ 'N RP3R$. As another poster said, classes aren't sacred cows of D&D, they ARE D&D. You can petition a newer edition of GURPS or HERO or whatnot if you so badly want a classless point-buy fantasy RPG, which favors powergaming.
That raw, seething hatred of point-buy D&D aside....
I figure 4th Edition D&D will either keep the 11 core classes of 3E, or shrink the number to 4, 5, or 6 core classes with more flexible roles (though that's not what I would favor, it's still a definite possibility). I.E. Fighter, Rogue, Priest, Mage, Champion (combination warrior and spellcaster, with spellblade/duskblade options, hexblade options, sohei options, ranger options, paladin options, blackguard options, etc.), and Adept (warrior mystic with decent skills, less combat focus than Champion, with bard options, monk options, ninja options, etc.). If sticking instead with the better and more-newbie-friendly 11 core classes, they're as likely as not to either remove 1-3 (i.e. ranger, paladin, sorcerer, making the former into PrCs and the latter into a specialist wizard/mage option) or add 1-4 (like a duelist replacing the OA samurai, CW swashbuckler, etc. as a nimble, acrobatic, and socially/politically-savvy warrior, along with a blackguard core class, and maybe a marshal core class and/or spellblade/'gish' core class and/or a 'sneak/skulk' or 'expert' core class as a less-assassin-ish derivative of the rogue). If keeping most/all of the core classes, I expect they might alter the sorcerer to resemble the warlock and favored soul in some regards and be made into a spontaneous caster with special bloodline/gift/transmogrification traits and a choice of receiving their spells from either divine sources or arcane sources. I also expect they might make the fighter a more appropriate option for a knight, mercenary, or heavy-armor/cavalry-style of samurai.
Going with a more-classes-is-better approach, but with most of the newer/updated classes being presented in supplements rather than the core rulebooks, is most likely since it will provide a steady stream of profit to Wizards of the Coast. And ditch the stupid concept of prestige classes as the premier method of customizing a character concept (since PrCs don't allow a concept to be realized at level 1 or 3 or whatever). Fix the multiclassing system, streamline the skills and combat and magic chapters, balance the durned feats already (I HATE 3.5! power attack especially!), and voila! 4th Edition.
Well, anyway, I guess my best guess though would be that 4E will have 10-12 core classes, with a minor possibility of it being 4-9 or 13-16 classes. My preference would be 14 core classes, I think, with plenty of other ones in splatbooks.
