Although the NFL has not officially announced which Week 17 game will be flexed into Sunday night, the only game that makes sense for the prime time slot is Green Bay at Detroit.
The Packers-Lions winner will win the NFC North regardless of anything else that happens the rest of the way. No other game is guaranteed to have playoff implications for both teams.
Four Week 17 games match teams that are already eliminated from playoff contention: Jaguars-Colts, Bears-Vikings, Bills-Jets and Cardinals-Rams. Those can obviously be ruled out of the prime time slot.
The 12 other games currently have playoff implications for at least one team, but all of them except Packers-Lions could lose their playoff implications before prime time next Sunday night. For example, Patriots-Dolphins looks like a good game right now because the Patriots are playing for home-field advantage and the Dolphins are playing for a wild card berth. But if the Raiders lose during the day on Sunday, the Patriots will have nothing to play for because that would clinch home-field advantage for New England. And the Dolphins could clinch a wild card either today or next Sunday based on the results of the Broncos’ and Chiefs’ games. It’s entirely possible that by prime time next Sunday, Patriots-Dolphins will be meaningless to both teams.
The last thing the NFL wants is a meaningless game in prime time to end the regular season. Which means Packers-Lions is the only game that makes sense for the season finale.