The Tigers demoted Chris Paddack to the bullpen last week, and with the way Charlie Morton has been pitching, he might not be too far behind. It was the right thing to do given Paddack's performance since he was acquired via trade with the Twins, and at least the Tigers have a fair amount of depth options.
Sawyer Gipson-Long, Keider Montero, and Troy Melton could all be viable candidates to move into the rotation full-time. Gipson-Long and Montero's track records as starters are a little sketchy, but even Montero's been better than Paddack or Morton on the whole.