Battlefield 2 has a very unique history. I would say it will leave a legacy coming close to CS.
I've been playing since release day, and not till around..... spring of 2006 did I ever get any good at it.
I am sure that very few games will come close to Battlefields gameplay, its history, its troubles, etc. I mean come on. What other game has gone through the hell that Battlefield has. With its series of will breaking patches, to its infuriating and insane online matches with CAL and TWL.
BF2 still provides a unique online playing field with so many players improving even I find myself challenged against the other guy who's good with the AK.
I remember playing with HawwK, Herby, and even the guy who started the clan roster thread for matches etc.
If there ever is a game like BF2, I will surely try it out. But my doubts stay with me.