For those unhappy with the quantity of sub-classes, I have a feeling that this is not the end of sub-classes - and in fact, this is one area where WotC may go a bit splat-crazy. We're going to sub-classes all over the place, in setting books, supplements, even adventures. They're also probably really easy to house rule, and I imagine the DMG will offer guidelines.
Silk is unforgettable. But I think he could be made with the Thief sub-class, maybe Assassin but I see more Thief.
I could be mistaken, but aren't sub-classes optional? A generalist wizard would be without a sub-class, perhaps?
But then you would give up all the goodies that come with taking a specialty! I think that wizards are rather generalist anyway. Unless the DM makes wizards only pick spells within their specialty, there is nothing stopping a specialist in one school from picking spells in another school. That seems to provide plenty of opportunities to be a generalist to me.