Although in the right mood, I don't mind the comedy of the 3 big names, their mere presence is almost guaranteed to reduce this to a schticky, cliched, steaming pile. Chock (Jock) full of mugging, hamming, and groaningly contrived slapstick.
Personally, I think a much better approach would be like "Harold and Kumar go to White Castle". That movie was funny as hell, with fairly unknown actors. Since they weren't Hollywood 'icons' the producers didn't have to fill the movie with any 'trademark comedy stylings' audiences expect from the well known actors.
So, I'm 99% sure they're going to end up turning an intersting plot into a bit of disposeable fluff. It depends on who's in charge of the levels of schtickyness... If they tone down Tim Allen to levels found on "Galaxy Quest", and the other 2 similarly , it might actually be good.