Sunni-shia will go on murdering each other like for the last 1300 years and sunnis are too many to succumb to shias.
Saudis will buy some nukes from Pakistan, since they financed Pakista's nuke program.
Iran will buy the knowhow or the physical warheads from NK.
Once one of the al Qaeda trasformation and ISIS defeated (let's forget the "moderate ones") Assad/Iran/hezballah will have only one part to recover, Kurdistan.
Nobody wants an independent Kurdistan, no Syria, no Iraq, no Iran and last of all Turkey of course.
Turkey will leave Syria in exchange for the destruction of syrian Kurdistan, Iraq will recover its "sovereignty", and bye bye the Kurds.
Unless Putin finds some use for them, maybe to keep everybody busy and worried with the Kurds.
The Kurds don't belong to any super group as shias (alawis) or sunnis, they don't have a free border from which to bring supplies.
They are done for.