The League probably isn't going to stop featuring the Lions and Cowboys on Thanksgiving, just too much tradition involved. If they continued to feature the Lions after their 0-16 season, you can bet those games are etched into their scheduling algorithms. As far as the 9ers vs Seahawks, I wonder about the sustaining power long term of the so-called best rivalry game in sports (not just the NFL).
Just imagine the NFL locking into this game and in 5 yrs or so, the NFC West turning back into the NFC Worst. Would the country really have been salivating for the Mora led Seahawks vs the Mike Singletary led 9ers?
As a Seahawks fan, I love it since the travel is short and the extended days off until the next game as well as the prime-time opportunity. As a league, I would take it year-by-year. In the 2000's and until recently, everybody nationwide was salivating over Steelers/Ravens due to the big personalities and ferocious physical play. Now that belongs to Seahawks vs 9ers.
Just some random thoughts. I wouldn't complain if they made the game a staple. Or at least consider it for the next 2-3 yrs.