#3 Might never be cleared to return to the ring: Nikki Bella

When Nikki Bella announced her retirement from wrestling, she didn’t reveal the full details as to why she has taken this decision. However, when she spoke to Jimmy Fallon on The Tonight Show, Bella stated:
“I herniated the disc above where I had surgery, I have all this inflammation around the metal and then I have a cyst on my brain. So they were like, 'you're done, no more.' So I didn't get a choice, which sucks.” (Credits to Wrestling Inc for quotes)
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Another Superstar who faced this situation was Paige, who is also retired, and while Nikki Bella still hopes to wrestle again, WWE can’t put her life at risk. Neck injuries are one of the worst injuries in wrestling because even when a wrestler recovers from it, the effects last forever and they only get worse over time. But as they say, never say never (especially in WWE).
#2 Could announce their retirement next: Kane

'The Big Red Machine' Kane once used to be one of the scariest wrestlers in WWE - until they turned him into an authority figure back in 2013. The past few years haven't been great for the former WWE Champion, as he never really got featured as much as his kayfabe brother, The Undertaker.
Well, WWE has their reasons for not doing that and we are not talking about them here.
Last year, Kane got elected as the Mayor of Knox County, TN which has increased his workload by a lot. Although he did return to WWE for a match at Crown Jewel where he took on D-generation X along with The Deadman. Kane and 'Taker lost their match and since then we haven't seen the former in the ring. He is already 52-year old and because WWE doesn't feature him on television a lot, it makes sense why Kane might retire soon.