I don't think this will ever happen. They may starting using Swift or some other newfangled language like Rust for some components, but it's almost never a good idea to rewrite something in a different language, and C++ is still the gold standard for this type of project.

This is often cited, but it seems like there has been very little movement toward swift since this tweet.

They were/are waiting for better cross-platform support. When they decided on Swift, using it on Linux had just recently become workable but it still didn't have feature-parity with apple land.

To me that all sounds like wishful thinking on their part. But I have a lot of faith in Andreas and the team, so I'm willing to take their opinion over my knee-jerk reaction shrugs.