There won’t be a “Caliphate” in the Middle East anytime soon. Islamic countries are typically unstable and rife with internal squabbles among various religious and tribal factions. That doesn’t change — and usually gets worse — when you remove the non-Muslim leaders.
They believe differently and will kill millions to prove you’re wrong.
There have been Caliphates before and yes they always fall. From internal strife caused by corruption and the general disorganization their culture is known for.