CB room is so thin, I don't see them dumping our only big nickel/relying on Jammie in year 1. Plus Chinn was up near the LOS basically playing LB last week as well
You can also call up 2 practice squad players a week at any other position, the emergency QB has to be on the 53. Some teams will probably gamble with some backup/special teams guys on the practice squad in order to keep the 3 qbs on the 53