Quoted from tamoore:
If Stern ever let Trudeau do his Beatles pinball
I don't think Stern is the limiting factor, it's the license holders.
I really don't think there's any theme that would hit every single audience market. Every licensed theme has it's fans and haters, and Stern has done pretty well to balance it out to get most bang for their buck with buyers (band theme, comic theme, movie/tv theme, car license).