If EA and Harmonix get enough pressure from the fans of RB then it could be made. SimCity "5" is being made after 10 years of nothing. Its being made due to a large fan base and how that fan base kept SimCity 4 alive through mods and UGC. Also the market for Rhythm games has cooled down and now would be a good time as the only rhythm game out there right now is the Rocksmith game and I believe that game is a PS3 only.
EA has nothing to do with RockBand anymore
my love is like a candle, if you forget me, i will burn your damn house down.