Fusible took note of the registrations, going on to mention that EA owns most of the Battlefield domains between one and 20 now. Battlefield 4 is expected to launch later this year.
Although the initial instinct may be to call this long-term planning a little overdone, it's not so crazy if Battlefield takes the annualized approach á la an EA Sports title. Battlefield '14 through Battlefield '20 doesn't sound so crazy now.
Update: Rock, Paper, Shotgun has picked up Battlefield21.com in the starry-eyed hopes of cashing in. It's a gold rush, folks. Don't get left behind!