I have nothing against the idea, if implemented, so be it. But I'd rather elements keep their flavour and their niches, Water has "Purify" allowing it to heal in a pinch, Life has strong healing cards, as it should be, Darkness can take some of your life to replenish theirs in a very vampire-like way.
I'm sorry, but in the crucible, due to my personal preferences, it might not get my vote.