I think its worth bearing in mind that professional sports people compete injured all the time, and “career ending” can mean a lot of different things.
Eg I don’t think we’re talking never be able to walk again type of injury - but it could just be something that he will lose range of motion, or be in pain until its fixed surgically and then once fixed he won’t be in pain or will have full motion but its not safe to risk the repair from that point on.
And, of course, the whole thing could be a work :)
I’m not convinced Jade leaving is so bad for AEW. She has a great look and aura, but in matches & promos wasn’t all that good and wasn’t going to get better there. She might not get much better in WWE either, but they have far more tools to deploy training her. I think she was pretty much already at her AEW ceiling and had to spend time elsewhere to improve.