[ZenGum]

I forgot to mention how many of the great cities are multi-ethnic.

Czechia and Slovakia had a reasonably straight border that produced roughly convex country shapes with the majority of the ethnic sorting already done. The former Yugoslavia didn't. Consider also the partitioning of India/Pakistan.

This could get quite messy.

And how much will the great powers get involved?

See, here's where a long term autocracy would have benefits for the US. Over the next five years the US government could spend, rough guess, a trillion dollars in a process of banning oil imports, and subsidising the creation of an alternative fuel network on eg hydrogen, biofuel, electric etc etc.

But that would be an outrageous interference in the natural market system, and a huge waste of taxpayers' money.

So instead, over the next five years, they'll spend two trillion dollars on building military capability and using it to "stabilise" the middle east, because the nation needs the oil.

Wouldn't it be nice to be able to simply walk away from the greater middle east, let them sort their shit out in whatever way seems fit to them, and maybe just take a humanitarian interest in the people there?