Successor to Muhammad?

I'm not a Muslim, nor have I studied a great deal regarding Islam. However, when I read that Al Qaeda now has to either fight ISIL or submit to their Caliphate or rule I was puzzled by what I heard.

I guess somehow someone (anyone) doing what Baghdadi just did commands respect? among Muslims who want a Caliphate.

But, if it is a Sunni Caliphate it also means that all Sunnis can execute all Shias as non-believers? If that is true then Sunni fighters who want all Shias gone as Blasphemers are going to flock to the caliphate to fight for Baghdadi as their Caliph?

I think we are seeing something here that Iran might be willing to mobilize it's armies to end. However, what will Sunni countries like Saudi Arabia, Turkey and Jordan and Egypt do? It is very puzzling to me because we no longer live in the 7th century AD.

(At least 90% of the human race doesn't).

So, is the U.S. , Russia and Iran just going to send in drones to take out pickup trucks with hellfire missiles or is someone just going to nuke Baghdadi out of existence?

What I just said about drones and nukes isn't any crazier than the first part about what is actually going on there.