I absolutely think there will be a BF3, and will possibly, or even probably hear something about it this year. Although I don't think we will see the finished product for release anytime soon.
Main reason is that EA loves money. They've got a brilliantly successful franchise there, and they aren't about to let it slide, or to terminate it's future potential. DICE/EA have moved out a little with Battlefield: Bad Company, and Battlefield: Heroes, and I think that these titles are just part of an overall strategy. Bad Company uses the propriety Frostbite Engine, and seeing how well it has done there, it will no doubt be used for some futher upcoming titles.
Logically, the time is about right for the next installment of the "serious" Battlefield series. BF2 was released in 2005, BF2142 was relased in 2006 - its now three years later, and FPS titles are still hot property. COD4/5 have been runaway successes proving that pure shooters demanding high-end PC's are still finding a very strong market. It just doesn't make financial sense for EA to NOT make BF3.
About this time last year I shot off an email to DICE about the future of the BF series. While I don't feel I'm any sort of authority on this topic, I felt I had a good enough idea to share with them. Essentially I'd love to see the next BF game presenting the players with the option of playing in ALL of the currently represented battlefields. So you fire up a game, join a server, and you're flying Spitfires against Panzer tanks on El Alamein, next map, you're fighting in the jungles of Vietnam, next round, Modern era warfare - followed of course with the 2142 setting. It would allow servers to focus only on one era if they wanted, or to potentially allow any weapons on any maps. Versibility like we've never seen before.
However, I think that'll be just too much to hope for. So here's my real hope and ultimate expectation. BF3: Cold War.
Imagine a full conventional war game of the Battlefield style, set between USSR and the USA, air, sea and land! There's never been a better time for dynamic and exciting "war" than the eighties!
Sure there wasn't any major, gameworthy theatres of war that took place during this period - but that in itself opens the possibilities up so much more!
F-111's, A-10's, Mirage F1's, Apache helo's, Kilo class nuclear submarines... and some seriously cool urban warfare! All potentially to the best soundtrack ever!
Real modern warfare is too hands-off for dynamic and exciting games. It's a whole lot of fun to be dealing out the punishment, but to create a balanced battlefield, I can't think of a time when both sides weren't so evenly matched!
That's what I hope we see with the yet to be announced BF3.
Oh, and this is what I heard back from DICE last year
Originally Posted by DICE
We can tell you that we have four games under development at DICE: Battlefield Bad Company, Mirror's Edge, Battlefield Heroes and one more project that is secret for the moment.