Given how badly Nemesis was received, both at the box office, and by the fanbase, I seriously doubt they'll dredge up the B4 stuff in any meaningful way. It's either going to be a few lines of dialogue explaining how Data has been reincarnated in some other android body (Lore's, B4's or a brand new one either found or built), or Data is part of a holodeck program, either one personal to Picard or perhaps part of the same museum exhibit as the Captain Picard Day banner.
I'm actually beginning to settle on this as more likely than him still being alive.
I'm actually beginning to settle on this as more likely than him still being alive.