EA has announced new dlc packs to be released for Battlefield 3 throughout this year. Each pack will come with it's own theme for the maps:
- Close Quarters
- Armored Kill
- End Game
Looking at the names, you can probably guess what most of them stand for...
The close quarters pack will have maps that won't include any vehicles, and well be... well close quarters. They're aiming to make it so that you feel the world around you is crashing down, making it so that anything from furniture to walls are destructible. The closeness of the battlefields will make it more "competitive," at least, so they claim. I'm hoping they'll be working on decent spawn points for these maps; I don't really look forward to spawning right next to an enemy and dying.

The maps will be much smaller than standard maps, and will be for 2 - 16 players. We'll also see some new weapons, assignments, and dog tags with this dlc pack! This should be released in June. Here is a small preview (that may have been recorded at the gdc):
Armored kill focuses on bigger maps, and will include the biggest map
ever in battlefield history. Hopefully it won't be overly big, and you'll actually be able to get in a vehicle! This pack will also include new tanks, ATVs, and other vehicles. They're trying to make it so these maps will have more vehicle "mayhem"/frays. Armored kill is set to be released sometime this fall.
As for End Game, one can only guess! (as they haven't released much information as of yet) This one will be released in the winter... and title to me sounds like it'll be the last of the dlc packs to be released.
Now, as for the paid subscription, nothing has been said precisely about it other than:
Frankly, I gave a compliment to one of our competitors. It’s got a subscription on the back end of an FPS title. I think that’s a best-in-class performance.
And John Riccitiello also noted that ea has been working on something similar to this, called Ultimate Team, for FIFA
The reason this is such a fast-growing revenue stream for us is we’re identifying and implementing best practice across the range of our products, and you’ll see lots more to come including an announcement near term that Peter just alluded to.
This was said about a month ago, and they didn't mention anything about it during the GDC, so we may not see this in Battlefield 3, at least not for a while. However, I wouldn't be too surprised to see something like this in their next battlefield game. I'd rather not see this come into play for battlefield 3, unless all the kinks are worked out and they fix other issues that are currently in the game.
You can read more about it all
here and
here for dlc, and
here for the paid sub.