I suspect schemes are just a way of requiring fewer decisions to make a rogue. If you think about it, "skill selection" is now an optional part of character creation because characters can just get skills from their background (and maybe theme). If rogues are supposed to get "extra skills", then that character class gets the same complexity WotC is trying to design around. I suspect schemes are just logically connected packages of what would otherwise menu-style class abilities.
As far as other classes are concerned, I'm not sure the same concept is necessary. Do wizards need schools? Maybe its a useful optional concept, but it seems like they could just select the appropriate spells. If there are schools, maybe they are just predefined spellbook selections? (Or maybe they are a limited spellbook selection along with one or two bonus class abilities?)
Similarly, you could pick a fighting style for fighters, but the simple-default version of that is probably just a bunch of static bonuses. (As it should be!) For a more complex fighter, it seems like you pick a theme to get access to a set of maneuvers. Surely, choosing the maneuver set itself is the right place for customization?
Anyway, this is all speculation. We'll learn more tomorrow.
-KS