[Avamander]

Saying "never" is too bold. But it's definitely getting immensely difficult.

There are still plenty of other flaws besides memory unsafety to exploit. I doubt that we'll see like a formally proven mainstream OS for a long time.

[MBCook]

True. But if developing an exploit takes 15 years and the average life of the device is five then to some degree that is effectively perfect.

[wbl]

Those flaws get harder the more restricted devices are.

[bigyabai]

Depends. If "restriction" means "complexity" then you may end up with scenarios like the BlastDoor vulns (eg. FORCEDENTRY).