It's really not that long of a season. NFL is by far the shortest season of all major sports, not talking about games which is obvious, but the overall length of the schedule from September to the first week of January. People just got used to the 16 game season. Where they went wrong is not going to 18 games with an extra bye and short preseason from the jump. If rest is that important teams will adapt by sitting players for rest like all other sports do.