You didn't really think Guitar Hero was gone forever, did you?
Activision said they wouldn't release any new installments this year, and none are planned for the near future. But that doesn't mean it's gone forever: in a recent GamesIndustry.biz interview , Activision VP of developer relations and acquisitions said the blockbuster franchise is only on "hiatus:"
"Actually, just to clarify, we're just putting Guitar Hero on hiatus; we're not ending it. We're releasing products out of the vault. We'll continue to sustain the channel; the brand won't go away. We're just not making a new one for next year; that's all."
What began as a multi-billion-dollar series has now become a liability in many ways. Activision cited music licenses as one of the many disagreeable costs associated with the games in question, and gamers and analysts cite over-saturation of the market. Music-based games were everywhere and eventually, interest just died out.
That being said, it could rebound. And that appears to be Activision's plan: wait for a better time and perhaps more advanced technology.