What would prevent the NFL from expanding to a 19 game season?

Question

There has long been team discomfort in Thursday night and international games because teams have a reduced rest period. A 2 bye-weeks schedule was attempted in 1993, but was dropped, it seemed in large part due to the excessive disruption within each team's schedule. Thoughts of expanding to an 18 game schedule (likely removing two preseason games) were hinted at by Roger Goodell during the 2016 season, but were tabled for the time being. The big barrier was likely player agreement given the increase in games played and wear-and-tear on the bodies, but an additional issue was that the scheduling would become imbalanced relative to the symmetric format used now.

However, if the NFL instead added 4 extra weeks to the season made up of 3 games and a second bye week, it would

• Allow teams to maintain a symmetric schedule (either by adding a second intra-conference division or matchups with equal position teams in the opposite conference)
• Increase the overall game-to-rest ratio
• Allow the NFL to schedule bye weeks for teams the week before playing in Thursday night games, as well as adjacent to international games.
• Allow weeks of the preseason to be eaten up, and also expand the season further into one of the seemingly-ripest lull periods (particularly in the less bustling cool season) in American sports, January and February.

Are there any complications, other than the player concerns of adding more games, that would hinder this scheduling change option?

Answer 1

At the moment (2017) the agreement of the NFL Player's Association (NFLPA) is the only roadblock that would preclude changes in the structure of the season.

The reason is that the union negotiated the limits to the regular season in the last Collective Bargaining Agreement (CBA). Article 31 of the 2011-2020 NFL/NFLPA CBA states that (link):

ARTICLE 31 ADDITIONAL REGULAR SEASON GAMES

The League and/or Clubs may increase the number of regular season games per Team above the standard of sixteen (16) only with NFLPA approval, which may be withheld at the NFLPA’s sole discretion.

Therefore, the change to 18 regular season games scheduled above can't happen unless the NFL negotiates with the NFLPA and gains the union's agreement, as stipulated in the CBA.

The players and the union might agree to a longer regular season schedule only if they gain additional concessions from the league (e.g., more money, better pensions, etc.). Most likely, any changes to the schedule will come with changes to the next CBA (see this article as one example):

With 256 current regular-season contests drawing fewer viewers, one very simple way to pad the total numbers will be to add another 32 games, which would carry with it two more weekends of prime-time action. Even if there are fewer total viewers or the same number of viewers watching less football (I still can’t figure out which one is worse), giving them more football increases the chances that any given prime-time game will be more compelling, more competitive, more exciting, and generally less Jaguars-Titany.

Ultimately, it won’t happen unless the union agrees. Although the official position for years has been one of total disinterest and at times outright refusal, the NFLPA realizes that everything is negotiable. With, for example, larger rosters, a bigger piece of the pie to pay all players, and maybe a few other concessions (neutral arbitration, anyone?), the players could be willing to accept the terms.