As much as I like BM, he isn't coming back. It always takes time to get adjusted to a different actor. What makes it harder is Billy is so angry which makes it difficult to like him. Didn't even like the character all that much in the last couple of weeks as he had so much hate & anger in him. Once things simmer down, I might like DT more as I would like to start seeing the old Billy.
Billy Miller has wanted to do other things for a couple of years. TPTB said no this year. He wanted other things more than Y&R , good for him. Good luck Billy, I know you will land it and be happier than you have been for the past year.