EDM or big room or however you like to call it might slowly run out (I'm not sure if I agree on this though), but there will be another very commercial style coming up after that and taking its place. it's what happened when trance started dying down and EDM took over, just that at the same time, the USA finally properly discovered electronic dance music.
and whatever that commercial style of dance music will be, it'll probably fit ushuaïa just as well as EDM does now. ushuaïa is simply perfect for that - a festival-like set up open air place and very very attractive to ibiza newbies.