I don't really think other than Rock that they are going to get big names from the past to wrestle. I just don't see Austin doing it at age 62 or whatever it will be for him. Undertaker just had a heart attack. HBK getting his knees replaced. HHH is on a pacemaker.
I do think it may be worth eyeing some AEW contracts though. Jericho is already rumored to be leaving AEW, I could see a big deal for him to guarantee him for the Mania 43 show. When does Adam Copeland's contract come up?
Rock vs. Roman, Cody vs. Punk though I think will be enough to headline.
I also think they'll get Cena back in the ring too for this.