Not sure if any of you follow Niner Nation, otherwise, this is just a random fan guess, not a regular fan piece for you: Why 49ers-Seahawks will not kick off the season on Thursday Night Football - Niners Nation
See you on September 4 in Seattle | ProFootballTalk
Broncos-Seahawks could start 2014 NFL regular season - NFL.com
Until someone can give me a better reason then the NFL doesn't want to waste a matchup like that for the 1st game then I'm saying it's the Niners/Hawks Week 1. Money trumps all. That NFC championship game had a higher rating then the Manning/Brady game. NBC would be sure to ask for that to be the opening game knowing that it would be guaranteed huge ratings and huge money.