Harmonix has continued to fiddle with Rock Band 4 since it released the game last year, but it's got something more significant planned for later this year. This fall, the studio (in conjunction with new co-publisher PDP) will release Rock Band Rivals, a $30 expansion.
The studio is staying mum on any other specifics at the moment, saying only "we’re going to be bringing you brand new features that have never been seen in Rock Band before. These are really big, new modes to the game, and players of all difficulties and play styles will be able to enjoy what we’re cooking up for you."
Harmonix also took the opportunity to reveal some new equipment for the game, including the new, foldable Fender Jaguar controller:
In addition to folding for easy travel and storage, the Jaguar includes improvements to the strum bar and auto-calibration sensor. It'll retail for $89.99 with Rock Band 4 and Rivals or $69.99 on its own. PDP will also release a $30 charging stand for the Jaguar and $30 adapter for legacy wired instruments, most excitingly the ION Drum Rocker. Lastly, the company is creating a bundle including Rock Band 4, Rivals, a Jaguar and drum kit for $199.99. Like Rivals, the equipment hasn't been specifically dated, Harmonix is currently aiming for "later this year."