Not a Great rom com but.....
I think a real full on parody about a washed up pop star, performing at crap small venues, eking out a living, could be very funny, starring someone like Ben Stiller or Jim Carey. seems like a great idea that hasn't been done before. Of course the character would be way funnier if they weren't self aware like Grant was in this film. But rather they are clueless as to how far they have fallen, and still talk and act like they are on top of the pop charts. It seems to be an idea absolutely ripe for a solid parody.