The publisher already held ownership of domains all the way up to Battlefield9.com, but their legal department decided to snatch some more just in case. Pure numeracy is cool, who needs subtitles?
Battlefield 20 may sound a little far-fetched but just look at Final Fantasy, and EA certainly aren't shy about serialising the heck out of their sports franchises. FIFA 13 anyone?
The domain name registrations were acquired May 2nd through brand protection group Corporation Service Company, who has even more Battlefield-related web addresses to its portfolio. EA spent $80,000 to acquire the Battlefield.com domain. Some are owned by those not related to EA.
Battlefield 4 is expected to release this fall, with speculation on October 29th.