Didn't I read that all the high-dollar voices for Ghostbusters had already been recorded and paid for?
Aykroyd and Ramis wrote the script, and they, Murray, Hudson, Potts, William Atherton and Brian Doyle-Murray have recorded voiceovers and provided their likenesses, yes.
Hard to believe they wouldn't follow through with something they've already invested so much in...but I know such things DO happen from time to time.
They're not common in the game industry, though, especially not when a publisher (Sierra) had to pay a significant amount of money to get the IP license in the first place. Based on Sierra PR comments earlier today, I'm sure the game will be sold off to another publisher (possibly even back to Sony, which could use another highly touted PS3 exclusive).