I was told, and this is a rumour, that Bill Murray will only do it if he becomes a ghost….really? What do you think?

That's a rumor from like 1999. Its not true anymore, and we'll never really know if it ever was.

you know what I think would be cool is if Bill wanted to do a cameo is have oscar go to central park as a full GB and play chess and say something like “your move old timer” and have the camera turn to see bill murray and have the two chatting it up and ending the movie I dont know just an idea insted of killing him off

Doctor Venkman;153543
That's a rumor from like 1999. Its not true anymore, and we'll never really know if it ever was.

I do think it was true at one point, but I also just read a quote from Ivan Reitman something to the effect of " marches to the tune of his own drummer and that tune changes quite frequently."