Harmonix built quite a music gaming platform around the Rock Band store and Rock Band Network. Even Dance Central is getting its share of consistent DLC.

Wouldn't it be a shame if Viacon's sale of the developer meant those endeavors died?
Luckily, Columbus Nova, a privately held investment group has purchased Harmonix and will allow them to do what they do best, which is make awesome music games. Co-founder Alex Rigopolous said:
We're excited for Harmonix to return to its roots as a privately held and independent studio. We are extremely grateful for Viacom's support, and proud of the work that we've done in partnership with our colleagues at MTV Games over the past four years to launch Rock Band and Dance Central. We're excited to continue work on those franchises and to continue to innovate and entertain in the coming years.
Don't worry, you'll be able to continue building your library of songs to interact with for a long time to come.