Iran can draw more aggro if they want but theyre getting pretty fucked as is and probably dont want anymore countries pilling on.

China doesnt care about iran and theyre winning by not being involved while the other super powers get bogged down in war and internal conflict.

Russia doesnt have anything left to increase vs Ukraine unless it goes nuclear.

WW1 was started because both Austria-hungry and Germany (partly) wanted a war. The assassination was the excuse and not the reason.