Why Apple Is Quietly Rewriting iOS in a Language You've Never Heard Of

The rewriting: quite believable, but it will take a looooooooooooooong time, and their goals may change looooong before they get there.

It not being Swift: unlikely, IMO. They’re spending lots of resources on Swift-C++ interoperability, added lots of low-level stuff to Swift, and advertise Swift for embedded use on Swift.org,

I don’t see what another language could bring. I also do not see them rename embedded Swift to something else; it’s hard enough for them to make Swift get traction outside their ecosystem already.

Also note that the “New Apple Language (hypothetical)” sample already is valid Swift code.