According to online news, including both actors, this is the plan for season 9.
Lincoln has said he will only appear in 6 of the planned 16 episodes of S9 then he is done forever. He did not reveal what might happen to his character.
Reedus meanwhile has being offered a large pay rise to take over as the main lead.
Kiss goodbye to the comics timeline sounds like A non comic character is now the focus, and both of the main comic characters Carl, and now Rick are gone forever.
Also Lauren Cohan (Maggie) will only appear in 6 episodes as well. While its not confirmed she is also quitting she did publicly say she is holding out for a new contract. AMC may cut ties with her rather than do that is the rumour.
Neither Rick nor Maggie will be the focus of nor even appear much in S7.