bladeofBG: This is excellent info, and thank you.
I don't believe a genre such as a space-sim (with combat, at that) could 'die' while space based RTS's flourish, as they're almost one in the same with negligible differences. Thus I think Freespace got a tough marketing break, back 13yrs ago despite being related to the Descent series and being a Black Isle game to go with Fallout 1. I'm tempted to write FS suffered the same fate as Planescape: Torment, but that wouldn't be accurate as FS is a game that ALWAYS has a market since the days video games started with Coleco & Atari consoles, and PS:T was an incomparable game (and still is) that proved to be ahead of its time. Rather, to say the least it appears someone dropped the ball bigtime in the PR department on FS' behalf, as this game and it's sequel seem to have it in them to have given StarCraft much more competition than they did; I think they could've provided competition on par with what Elder Scrolls and the Might & Magic games of the time gave to Diablo & Baldur's Gate.
Well thankfully, GoG is giving Freespace & PS:T a 2nd life, somewhat righting past wrongs! StarCraft 1 & the Freespace series both look freakin awsome, for space-based combat games.
No problem ... however, as someone who was playing space and flight sims in the 90s I can tell you that the offerings of such games from major publishers today is minuscule when compared to the height of popularity for the genres. For instance, in those days, it was expected that a gamer would have a joystick as an essential peripheral. These days it is assumed that few gamers will have a joystick. Flight sims especially are consistently referred to as being a very niche market and space sims are sadly not doing much - a little, but not much - better. The "fall" of the space sim is fairly well documented and started around the time Freespace 2 was released. Wing Commander, the X-Wing series, Freespace series, etc ... were all pre-2000 and few space sims have been major studio releases since nor has the volume of offerings been what it once was. This is not to say that there haven't been great space sims released since then, but in terms of developer size and target audience size they've been mid-tier games and again they've been few and far between.
RTS games meanwhile have remained very popular as a genre and the genre has even broken into the coveted "casual" gamer market with tower defense games. While space-based RTS and space sims may both be science fiction and feature combat quite heavily, the gameplay differences between them are substantial with space sim combat being essentially a dogfighting simulation (newtonian or not) and RTS games being about micro/macro control of units and bases. I like both, but the genres could not be more different in terms of gameplay. If anything, the gameplay of a combat space sim shares more in common with FPS games like Halo than it does with SC, and probably the meteoric rise of FPS + FPS/console games in the last decade and a bit helped contribute to the fall of space & flight sims (and several other genres). This is just the way it works in any entertainment field, genres of all types rise and fall in popularity - in another decade who knows who will be king of the hill in the gaming world?