You missed the point or I didn't explain correctly. It's not just the ISA, although jumping back and forth between them would not be smart. The issue is if you go x86 you have no option but to buy from Intel. You can't make your own processors, you can't buy from multiple vendors. Ever.
No, I understood your point, but it just doesn't make any sense.
If I am <Insert Phone Vendor Here> and I choose an Intel X86 CPU for my <Insert Phone Here>, then that particular model will run Android and will be powered by an X86 CPU.
Say, in the next generation of SoCs, Intel's X86 chips aren't up to snuff. So what do I, as <Insert Phone Vendor> do? Well, gee, can't I just go to Qualcomm or MediaTek for chips to power my next generation Android phone(s)? What makes it so that I "have no option but to buy from Intel," what relevance does "making my own processor" have, and why can't I buy from multiple vendors?
As far as Android is concerned at this point, X86 and ARM really are the same (with ARM obviously having better native app support, but Intel is throwing a lot of money at the problem to make sure that all native apps come compiled for X86 as well as ARM), which is why your argument makes no sense.