I hope JBL stays, but I think he'll probably move on. I think The Rock paved the way for WWE Superstars to leave the business on their own terms and to venture in to other fields (I know Hogan did it first, but the Rock's films are actually good and have been successful). As far as JBL venturing into other career fields, you have to just wish the man the best.
If he does leave, he'll have to go down as one of the best bad guys of all time. He put guys over real well. And he was great at working the crowd.