I picked up up the first single and listened to the intros a few times. I think it is a promising set. I am probably in the small minority who is actually really glad to see them phase µ’s out while they are still on top. I feel very pretty strongly that at least from a story perspective our time with µ’s has come to close, and I am glad they are not being used until we are all at the point where we are saying “Do you remember when Love Live used to be good?” I don’t know if you watched the movie, but even though it is fun it really lacked focus, and the major conflict was mostly recycled from season 2.
Besides, if they switch out Love Live girls every few years down the line they can have a crazy cross over movie where all of the Love Live groups need to sing at an upcoming Love Live. This is how they handle it with PreCure at least and it is ridiculous amounts of fun.