Exactly my point though. Apple is large enough that if they want to break from ARM in the future they can do so by forking an LLVM backend. That's not a large

Exactly my point though. Apple is large enough that if they want to break from ARM in the future they can do so by forking an LLVM backend. That's not a large job if it's a very small change, but once it's been done once they have plenty of resources to provide ongoing support (like they do for webkit). The dividends of doing so are potentially massive. Given that they've been able to make really large gains with the A series chips to date on mobile (not least because they've been able to offload tasks to dedicated co-processors that general-purpose ARM cores don't ship with), the rewards for having chips that are a generation ahead of other like-for-like computers will outweigh the cost of maintaining the software.