... would we all be using RiscOS on our Acorn A9000s instead of wintel boxes?
Or would ARM have been dragged down and buried with Acorn...
Hmmmm.......
I suspect the latter.
Apple wanted to use an ARM chip in the Newton but didn't want to buy chips from a competitor. 6 weeks later ARM appeared.
But that wasn't what made ARM, it was the business model thought up by the CEO they brought in.
They licensed the core to anyone who wanted it, and now there's hundreds of companies making ARM chips in mind bogglingly huge volumes (vastly more than x86).