There's almost 100% certainty Nvidia cards will drop in price in reaction to AMD's new line of video cards that are set for release in October. At least if AMD is competitive.
eh I wouldn't bet on that. Nvidia really hasn't proven they do this the past few gens of cards. I mean prices drop a bit over time but not much, at least no more then 40-50 bucks tops not including random sales.
Also is your computer really that bad? Your system still seems to be a pretty decent midrange machine. I can't imagine BF4 won't play just fine on high. I know it's nice to max every slider but in reality ticking a couple things down isn't the end of the world and not really worth spending hundreds upon hundreds of dollars to rectify when the in game the difference won't be that noticeable once the games in motion.
If you do upgrade I would go with a new CPU/MOBO since that looks to be the thing in most need of an upgrade. The GPU should still tide you over until the next gen of cards just fine.