Jim,
The ability is there to take FS2004 or FSX and create a full motion simpit..... all the realism you could want shy of a real Level D simulator. All it takes is
MONEY!

And maybe time.
Force feedback certainly COULD be replicated on a yoke.... but to put that into a yoke likely would change the price point from in the $125-130 range.... to maybe the $250-300 range. THAT would shrink the market instantly. So the payback commercially is not going to be there for the people like CH or Saitek to go after casually.
It is amazing how little details make a difference in the sense of immersion. I have what are known as "bass shakers" mounted in the base of the pilot's seat in the pit. They are transducers the create vibrations (not sound) that I can feel. I have the sound files tweaked so that when the APU is started, I get a tiny teeny vibration, when the engines are started I get a very slight vibration, and so on. I use Aerosoft AES services that puts in the sound when the nosewheel goes over the centerline lights. In the pit I can REALLY feel those vibrations on the runway. And same with touchdown on landings. When the rollout sound stops... the seat suddenly loses a lot of vibration as the aircraft leaves the ground.
Many things are possible. But take it one step at a time.
As to multiplayer issues.........
See the Multiplayer section of the forums. And please READ the stuff about opening ports. It is a pain in the butt to set up ... but it is necessary for OTHERS to enjoy the experience too.
best,
............john

Intel i7 960 quad 3.2G LGA 1366, Asus P6X58D Premium, 750W Corsair, 6 gig 1600 DDR3, Spinpoint 1TB 720