Apple is doing exactly that. They’ve already shipped stuff written that way. I think the Secure Enclave code is now Swift.

I’m pretty sure they have extra stuff on top at the moment to help them write ultra-strong/safe code that the released language doesn’t support directly yet.

But they are moving in that direction. Just because most people use Swift as a language where they don’t have to worry about memory allocation and with the large standard library doesn’t mean that’s all it can do.