The Guitar Hero series has already lived a bit past its expiration date, but the downloadable content train has finally come to an official end now that the April track pack is out. Activision community manager Dan Amrich noted on the PlayStation Blog, "With the release of April’s downloadable Track Packs, Guitar Hero as a franchise goes on vacation until further notice." Amrich is also giving away a Guitar Hero time capsule with goodies from the series.
In the comments, Amrich notes to one user that the packs will still be available for download anytime, so fans who are extremely late to the party can still dive in and choose from all the assorted pieces of DLC thus far. We just won't see any new track packs hitting in the coming months.
After Activision's earnings report showed plans to scale back the music franchises, it seemed that DLC would end after February. Activision then claimed that continued support led to more planned packs, which they've made good on.
This means an end to Guitar Hero for the time being, but probably not forever. Recent comments from Activision VP of developer relations and acquisitions Dan Winters said that the series is only on hiatus. "We're just not making a new one for next year, that's all," he said.