Especially magic arms and armor. The biggest factor here being the “resistance to non-magical weapons” being a ribbon ability at high levels…unless the creature has the means of generating anti-magic fields or something where that ability is likely to kick inYeah, I agree that I can't see a high-level game without magic items, so I guess they'd be there in some way, shape, or form. Still, I don't know how you can even come close to figuring out what the "average" PC will have.