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.
I’m sure you can find some COBOL code in many of the training sets. Not sure I would build my next startup using COBOL.