There is no rotation, and they don't want to, or will, trade Lynch.
I don't get why people don't understand this, but the Bills are finally doing what fans have screamed for over the years, they are going to be a power running team, and will use 3 RB's this year for their offence. The offence is going to be all about the running game. Fred and Marshawn will be the 1a/1b RB's, and CJ will be used all over as a RB and as a WR, anyway to get him the ball. CJ is going to get 5-10 carries as a typical RB a game, and get the same or more touches on screen passes as a WR. Lynch and jackson will both be the workhorses getting the brunt of the carries, and Bell will be the backup. This takes alot of the pressure off of Trent, and allows him to not have to force throws and try to make plays with his arm.