Even seeing the current arena screen, I don't think, that fire needs to be nerfed, since the skills do play quite a big role in those decks being nigh unstoppable.
Simply buffing everything else, would probably end in every element being able to do everything, thus being the same. So maybe a return to a weakness for the fire element might be the better choice. As for me personally, I would wait for the new shards and their influence on the metagame, and if fire still seems to be the romperstomper element, then I'd probably go for some finetuning.