Or maybe not….
I seem to remember news reports quite a while back that stated that Dan Ackroyd wanted to make it like no other. Unfortunately Sony Pictures is the obsticle in question. They own all the rights and they aren't willing to deal.
It doesn't really matter if Murray wants in or not. It's no fun watching a movie with a star who really doesn't want to be there to begin with. Ackroyd can just write around it (so long as he doesn't go over the top like he did with Blues Brothers 2000, which I actually liked) There was a rumor that Sony was testing the waters for a possible second sequal with the DVD releases two years ago.