The official RAGE Twitter account has confirmed that both Avalanche Studios and ID Software are working on the upcoming RAGE 2. This was first confirmed on the official RAGE 2 website (in the fine print).
Avalanche Studios is best known for the Just Cause franchise and more recently, they created the last entry in the Mad Max series. This makes sense given the fact that Just Cause is one of the most insane open-world games and the original RAGE was confirmed to Mad Max both in tone and setting.
We’re getting more RAGE 2 later today, when Bethesda reveal the gameplay.