It will be interesting to see how Iran reacts which will call for revenge.  It usually fights its wars by proxy.  Their only direct involvement as of late has been in Syria which has been a bloodbath for them. One can reasonably draw a conclusion that this is an attack on Shiia Islam in the very heart of Shiia Islam- the bombing of the mausoleum of the Grand Ayatollah Ruhollah Khomeini the father of the Iranian Revolution.  An uptick in the schism between Shiia and Sunni.  Iran would cast suspicion on Saudi Arabia and tensions might rise to open conflict.  This is all taking place as the U.S., the world's only superpower, isolates itself from these chronic conflicts.