It turns out that Bill Murray has been in talks to play the father (presumably of Reese's character), but then lost interest. Meanwhile, Nicholson has been feeling the acting itch, so he might step fill the open spot for the director who helped him win two of his three Oscars. This, however is far from a reality right now. As the news post states: "Nicholson's deals are known for being notoriously hard to close and this one is still in the early stages." So Jack could easily lose interest as well before production kicks off later this month.
I say have at it and then find Nicholson something juicy. I'm not talking about the gigs that got him his more recent work, but something edgier, in line with his work in Easy Rider and One Flew Over the Cuckoo's Nest. Wouldn't you agree?