There seems to be (at least) 2 things working against the Caliphate:

1) the need for independent armed groups, who all have carved out a niche for themselves, to surrender authority to another

2) the instability of the structure; with so much invested in the Caliph there will be a free for all to snatch the crown.

I'm willing to bet that this is a "flash in the pan"; it might perhaps survive as a myth of what might have been...if only...