Too old, Keaton. Do a Johnny Dangerously sequel instead.
I think Michael Keaton is one of the underrated actors in Hollywood. Although he does comedy well, he is also a great dramatic actor. Two of his best movies are "Pacific Heights" and "Clean and Sober". Considering that actors like DeNiro and Pacino can only play caricatures of themselves, I say Keaton is as good if not better than either of those two.
Which remeinds me I hope they never do another Ghostbusters sequel with the original cast. They are way too old to pull it off.