I don't know how they can improve the game. Better art and music, but mechanically its already as close to perfect as you can get. I don't think a better balanced and mechanically rich deck builder exists.
It may be pretty random but the top players are able to amass winstreaks on A20 and have a lot of decks go infinite. Monster train may be a more fun casual game but the really serious players figured it out and abandoned it rather quickly for being too easy.