If everyone goes back to where they came from, Olduvai Gorge is going to be crowded...
Israel has been the toy of nations since well back into biblical times; some Jewish holidays reference successful opposition against invaders (I know, I know, the Jews were invaders too, but where does it begin?) the Persians, Babylonians, Greeks (who owned the place before the Romans took it from them), Byzantines, Arabs, (actually, the area got taken and retaking by Byzantines and Arabs),Crusaders, and the Ottomans, the British, the Israelis, and who knows what's next.
The one thing holding all the Muslim nations together is the restoration of Al Kuds (Jerusalem), and the establishment of the Palestinian state. Paradoxically, if they actually achieved it, what would hold them together then? Careful what you wish for...