That they are still training models against Objective-C is all the proof you need that it will outlive Swift.
When is someone going to vibe code Objective-C 3.0? Borrowing all of the actual good things that have happened since 2.0 is closer than you'd think thanks to LLVM and friends.
Why would they not? Existing objective-c apps will still need updates and various work. Models are still trained on assembler for architectures that don't meaningfully exist today as well.