When the Israelis signed on to the JSF this summer they expressed an interest in a two seat version. They are the only ones to have done so and they may not get what they want. Lockheed says that the simulator is so good that they willl not need a trainer version.
As for the future of Marine NFO's, I think it is relatively secure until 2015-2020 timeframe at least. When the Marines started getting Hornets and retiring A-6's they made a concious decision to purchase F/A-18D's (two-seaters) to replace the Intruders. This made the short-legged Hornet even more starved for gas but it adds another set of eyes in the cockpit, which in many cases is invaluable. The D's do the FAC-A (Forward Air Controller-Airborne) mission very well. The Marines care about this becase they call in Close air support for the grunts on the ground, and the grunts are everything to them. The NFO in the back is the main reason they can do this. F-14's have done it too.
The Marines have no plan to replace the EA-6B Prowler right now, only the Navy. The Marines plan on flying the Prowler until 2012-2015. I have no idea how they will manage it because we are barely managing to keep them flying now. The Marines have a long tradition of tactical EW aircraft and I don't think they will give it up easy. They are reluctant to get the EA-18 because they want to go to one jet airframe. They have looked at making an electronic attack bird but it would be hard to do with only one guy. Who knows what they will do?
As for technology allowing only one guy to do the mission, I would disagree with that. I have a bias since I am an NFO but I will give you some examples. The French Air Force (don't snicker) changed their orders for the Rafale from almost all single seat to 2/3's two seaters after the Gulf War when their main strike planes, the Jaguar's, had difficulty hitting their targets due to high workload (the French are damn good, when they want to be). The French Navy did the same thing, from 60 single seat to 15 single and 45 two seat. The Israeli's have ordered 100 F-16I's, two seat strike versions. So have the Singaporeans and the Greeks. The main reason many air force's get rid of the backseat, too much money. It costs a lot to train even an NFO/Navigator. I think they lose out in the end though.
The CH-46 was supposed to have been replaced when - 1982???? If your MOS goes away, then you will be assigned and/or choose another one. By the time that happens, all of you will probably be senior captains and/or junior majors and there are a multitude of important (if less glamorours) specialities the Marine Corps/Navy can use you for (staffs, attaches, etc)
