Do some of you know the old ms-dos game "Strike Commander" from Origin? :D
IMHO lock-on2 needs some sort of very well written dynamic campaign combined with a good story. Don't get me wrong, I dont mean to turn this very well written piece of software into an arcade game.
Just look at Silent Hunter 3: this game is appealing to both subsim-newbs like me and die-hard sims and includes a very well written campaign mode. In one campaign mission you get points as reward and you can spend them on better equipment, torpedos or even a shiny new submarine :) Strike Commander had this feature years ago (although the story was linear and was pretty arcadish). In my imagination I see a game where you start as little mercernary with a old and rusty mig-21 or something like that and through jobs you can buy better weapons, flyables and so on (with still realistic flightmodels etc.).
EDIT:
Or anybody remembers Apache Longbow from Digital Integration? It had static missions, but the battlefield was always *full* with plenty of other ground units, helos and jets completing their own missions. I remember a mission where you had to laser-designate a bridge to guide a GBU from an f-16 :)
Damn I miss these games ;)
IMHO a successfull game has to be appealing for both die-hard sims and casual-simmers.