4. Trey Lance
How fun would it be to see Trey Lance take a snap or two against his former team?
Unfortunately, fun narratives aren't going to inform what Mike McCarthy does with the limited space on his game day roster. The current NFL rules simply make it entirely unnecessary to have three quarterbacks active.
Lance will maintain his usual role as the designated emergency third quarterback, making him eligible to play if both Dak Prescott and Cooper Rush are knocked out of the game with injuries (or are ejected). And since there aren't many situations we'd give Lance a snap over either one of those two while they're available anyway, Lance will remain technically inactive indefinitely.
Is there some room for Lance to contribute in short-yardage, goalline and maybe red zone situations? Maybe — his athleticism can pose some problems to defenses in those spots. But those potential fringe cases aren't worth an active roster spot, and if anyone is going to be prepared to stop a surprise snap or two from Lance it would be his former team.
It's a bummer, but there will be no revenge game in Week 5.