It looks like Apple has filed for a number of trademarks related to Beats, most likely related to Apple Music's radio feature. Specifically, filings are for the word marks of B2, B3, B4, and B5, along with associated logos, which are similar to the existing Beats 1 logo, as you can see below.
The applications were filed under the Beats Electronics brand, and are currently still under review.
It emerged earlier this year that Apple's deals with the record labels permit it to have up to five additional Beats radio stations, in addition to the existing Beats 1. The existing Beats station currently offers 12 hours of original live programing, with a repeat broadcast for the other half of the day. More Beats stations could offer a wider variety of music, in addition to anchor centers other than LA, New York, and London.