My guess is illusion will stay a stealth skill.
Yeah, I don't think that's a crazy idea, but I think Illusion has more of a magician's feel to it (it's more about casting spells), whereas Alchemy is more about knowledge of plants and such... So Alchemy fits with more of a ranger type class.
Another option is that Restoration could be a stealth skill - the thought here is that Restoration fits with a monk/cleric type class.
Probably the more interesting question is what's left of the stealth skills...