Others have already said it, but as someone who's level 50 all classes myself, I too must recommend at least getting the cross-over skills of THM, ACN, and CNJ. Swiftcast in particular is really good, allowing you to ignore any cast times behind any spell you cast (assuming it has a cast time) and just use it instantly. Most healers I've seen never leave home without swiftcast in their skill set. Allowing the healer to ignore the cast time of the rez spells and just get it off instantly is neat.
We don't know how AST will work, (Sounds like we'll finally have more info on that soon) but it wouldn't hurt to pre-prep yourself by leveling the other spellcaster classes.