Nothing is going to "kill" FH unless there is a better platform released and some very talented guys offer a WWII mod with air/sea and land vehicles but more features and graphical eyecandy......or the FH dev team falls apart and quits......
I don't think a better platform is going to be there for at least 2 years, i don't know any better platform then bf1942/bfv/bf2 when it comes to first person vehicle combat mixed with first person shooter game, all in one game.
HL2 has some player controlable vehicles, but not like bf1942 does. No huge battleships and carriers there......it maybe would look better but not offer the same features as bf1942/bfv/bf2 can.
Maybe only operation flashpoint 2 can threaten bf1942/bfv/bf2 as a platform for WWII games, but as far as i know they don't have ships neither. Soldner seems to have been dissapointing, and other similar games are not of the same graphical quality.
But it is a mistake to think the FH devs are alone in excellence, those that have visited BG42's website and have seen the new models and skins will be convinced that also is a quality mod, the days of ugly models and skins id over for them aswell. And on top of that, they have more types of land vehicles, Jagdtigers, Elephants, Hetzers, skirted versions of all kinds of Panzers and so on and so on they have, and for quitte some time and they are steadily improved. Their maps are more open and bigger, they do not lag and are better for vehicle combat ( but because they are very open not as attractive to bunnyhoppers ) Their damage system is FH + 1 hit....not so arcade at all. But they lack online players. Imagine guys like these would go over to another future game platform ( well they do within DICE products now, they support RTR and BFV ) and they might actually draw players from FH. Not happening yet, but they are a much greater "threat" then HL2 or another game. Enough that i am a BG42 fan also......and i am a realism freak.
Despite all that HL2 is likely going to cost FH servers if maybe temporarely, just because it is new and many players want to play it. Those who have enjoyed HL1 will buy/get HL2 without question.......it is not yet another fast-paced fragger/hopping game, it is a quality game.
I will without doubt buy HL2, i have enjoyed HL1 very much, even for years including CS and DoD. HL1 seems to have sold a staggering 8 million copies, and was rewarded with 50 game industry awards.....that is quitte a game, and now they have improved it with technoligy of 5 years later.......it's release will be felt....
But that will not make me forget about FH......i think no FH fan will be away very long because of other games......if he does, he was not a FH fan :lol:
Panzers keeps me busy now, and Wartime command ( was battlefield command ) may do more so, since it will be more realistric and with zoom detail up to FH size vehcicles and men. Only, these are RTS games, not FPS.
But with a much improved FH i will be right back, HL2 or no HL2, or other games......untill somebody can do better then the FH team ( a bit ungreatfull, but it is the truth and applies to almost all players anyway

) It must be a compliment to them up untill now no game ( besides BG42) could......