Hey, there!
Even though i havn't played it in several years, Battlefield 2142 was my favourite FPS game for a relatively long period. It's only downfall was that my computer didn't run it very well, and i was kinda bad at FPS games at the time. BF2142 is however the only FPS game where i had mostly negative kill/death ratios, and still had fun EVERY round! I think this is because of the balance, variation and posibilities the game offered. It had the basic Battlefield mechanics we have all learnt to love through BF2, but was not restricted by the limits of realism a "modern time" setting like Battlefield 2 and Bad Company (2) had. The Titan game mode was something completely new and inovative, and the Goliath added a whole new dimention to vehicle warfare.
Not saying that you want to go after "killing" games like Halo, but i think a new 2142 game would definitely apeal to both the sci-fi nerd and the FPS hardcore. People have (thanks to Halo, Black Ops, Crysis) learnt to accept bizare weapons and equipments in a whole new way since BF2142 came out, and with the quality-ensurance Battlefield stamp on it, a new 2142 game would drag a huuuge crowd of gamers, perhaps even those that stuck to Battlefield 2 throug the golden ages of 2142. Frostbite 2 has come a long way, and just imagine BF2142 with destruction 2.0 and the microdestruction you showed us in the Fault Line trailer! Thats a 3 (4, but Heroes won't register) times BF veteran's 2 cents, at least.
Have a nice day!