IMO - Next war will be on Syria because In case of war with Iran, Iran & Syria both will target Isreal and Syria can give heavy blow as it is very near. I am also not clear about the role of considerable Jew population in Iran - Will the support attack on Iran? If yes than how will Israel and US will ensure their safety, If not will they target Jews as well?
I think they will try to use Arab Spring type of trick with Iran rather than going on war directly, in this way they will not have any conflict with China & Russia.
Above are my thoughts, can be stupid as i am not think-tank at the moment