Once upon a time, the only Thursday NFL games you could count on seeing were the Thanksgiving Day specials. In 2006, the NFL Network began airing games on Thursday nights, a package that has since settled into regular rotation on the network. And, according to what NFL commissioner Roger Goodell tells SI's Peter King on "The NFL Podcast With Peter King," it's a package that could expand as soon as next year.
The expansion would not be limitless; Goodell tells King that he doesn't "see it being every Thursday of the season," and also that the league likely wouldn't expand past the current Sunday-Monday-Thursday rotation for games.
King speculates that the NFL could elect to keep October weeknights clear to avoid overlapping with Major League Baseball's playoffs and World Series, and might play a batch of Thursday games in September in addition to the current rotation beginning in November. The NFL also has a Thursday night kickoff game to open the season, which is separate from the NFL Network package of games.