Since his rather acrimonious departure from WWE last year, which was drawn out due to contract issues relating to his chronic knee injuries, Rey Mysterio has mainly been working for Mexican promotion AAA, and will appear in episodes of season 2 of Lucha Underground. However, due to severe pay issues with AAA, Mysterio has reportedly cut ties with the organization and is reportedly looking to return to WWE in some role. It’s almost certain that WWE will welcome him back, as Mysterio was a top merchandise seller during his time in the company, and WWE has had trouble finding someone to replace Mysterio’s influence with the highly-coveted Latino demographic (although they have recently found some success with current US Champion Kalisto).
While Mysterio is a big star with name recognition, he’s also decidedly on the down slope of his in-ring career, as multiple knee surgeries have left him extremely limited in his abilities. It will be interesting to see how Mysterio fits into WWE’s future plans if and when he returns.