From what I've read, I believe they're still sticking with the script Harold Ramis wrote a few years back, because it sounds like the same premise (passing the torch to a new generation story). And we're getting the original actors back (minus Harold Ramis obviously, R.I.P.), which had a big input into how the characters were portrayed in the original film.
So with a little luck, I think they can pull this off without ruining the franchise.