LIRR cannot move out of the existing station -- the new Moynihan hall will not have the capacity to handle all LIRR commuters. In theory Amtrak could move completely to Moynihan, but I doubt it. It is unlikely that the real estate developers will be willing to cede sufficient space in the Moynihan hall for all of Amtrak's crew and support spaces. Eventually, maybe next century (sorry, can't resist the sarcasm) NJT will extend the central corridor to the low numbered tracks providing a couple of more exit points per platform. Other than that, I am not aware of any improvements (including expansion) of the NJT spaces at Penn Station that are being discussed or looked at actively for the next 20-25 years.