There are still QB moves that will/need to be made in the coming days. Both Garoppolo and Mayfield should be traded in the coming days. Seattle is likely in some of those discussions, although it is much more likely for them to get Mayfield (between those two) as that would be out of conference/division. Mayfield may want Indy, but he may not get that choice. They get either of those two and they can compete to make the playoffs especially in the NFC.
Other former starters still technically available would be Winston (although he is now likely to return to New Orleans), Mariota, hell even Dalton or Fitzpatrick (if he is healthy). Any of those guys could give the appearance of competing and be a bridge QB.