Harmonix had developed previous titles in the acclaimed series, but has since been bought by MTV Networks for US $175 million in September last year.
Activision acquired original Guitar Hero publisher RedOctane, along with the licence, in May of last year, adding the music franchise to a highly-regarded portfolio of brands that includes Call of Duty, Tony Hawk and Spider-Man.
A spokesperson for Activision would not be drawn on the situation, offering: "Activision does not comment on matters of rumour or speculation."
Neversoft has been an Activision studio since 1999, and has worked on titles such as Tony Hawk's Project 8, Gun and Spider-Man.