Johan Andersson, better known as "repi" to the Battlefield community posted an update on his Twitter account earlier today. He stated that DICE has plans to develop Frostbite-powered games for release in 2013.
These games, he says, will absolutely require a 64-bit OS like Windows 7 64-bit or the upcoming Windows 8 that's set for release later this year.
"If you are on 32-bit, [it will be a] great opportunity to upgrade to Windows 8," he wrote.
There's no telling whether the company plans to release a Battlefield 4—or better yet, a Battlefield 2143—next year, but games powered by the engine will certainly require a 64-bit OS.
Regardless of his recommendation to upgrade to Windows 8, you won't see me upgrading to it unless it becomes absolutely necessary to do so.