Well, the horse's kinda already bolted out of the barn when they allow external scripts to be executed in game level updates or whatever. And any damage would b

Well, the horse's kinda already bolted out of the barn when they allow external scripts to be executed in game level updates or whatever. And any damage would be contained to the app in question... unless the iOS sandbox is a sieve... they do seem to have tightened it up fairly well recently though. You're right about power usage though. Even if they did allow third party engines, they wouldn't allow third party JIT compilers (much bigger attack surface, W|X memory protection is gated behind an apple-only entitlement) so those browsers would be second class citizens battery- and performance-wise for sure.