This morning, Harmonix announced that indeed Rock Band 4 is coming this year for the Xbox One and PS4. The game will be going back to the core Rock Band experience of just Guitar, Bass, Drums, and Vocals. Pro Guitar and Keys have been scrapped but pro drums will be returning for you kids who love your cymbals! All legacy dlc will eventually be returning too and if you purchased it before, it will be free of charge on the new consoles too.
For more information, check out Harmonix’s press release.