Unless they dedicate themselves to really commiting to Jamie Noble Boy, I think they'll be missing a key ingredient for getting the most out of Misterio: a dominant division heel. Some of his best cruiser programs were against Malenko, Ultimo Dragon and Eddie & the lWo because each presented him with an opponent who appeared to have him overmatched. Misterio was the ultimate underdog, and the combination of the "king of mystery" gimmick and his opponents went a long way towards establishing him as the resourceful, fearless hero-type who would have to find new ways to win.
Malenko was the technical master who could ground him, and when Misterio beat him, Malenko lost his cool (when he stole the mask and Tony Schiavone, of all people, had to defend the lucha tradition) and became more dangerous. Ultimo Dragon arrived with the J-Crown titles and was instantly sold as someone even more internationally prestigious than Misterio, who to that point was the top guy in the division that already had a pretty interesting international feel at the time. With Guerrero, he had to face a bigger, meaner opponent who had the backing of most of the rest of the cruiser division and essentially won that feud by joining and outlasting the rest of them, even though it cost him the mask (and most of the appeal of his character, I felt).
He apparently can't fly like he used to (though he really hasn't been able to do everything he used to for some time now, but who can?), but I think if he gets back in touch with the ultimate underdog hero aspect of his original WCW character, he just needs a dominant heel to put him in jeopardy and he can win over the crowd like he used to do on Nitro and PPVs.
He'd probably be able to write better stuff for WWE storylines than anyone else they have doing that now. I say the WWE should give Baghdad Bob the book, he couldn't do any worse than Sullivan or Nash did in WCW.