I’ve heard that New England might be an exception. Apparently Robert Kraft wants to use the World Cup as an opportunity to replace the turf in Foxboro with natural grass permanently.
Well, that demonstrates the point even more. The NFL doesn’t care about their own players.
The only reason for them to use the turf is if they're hosting multiple events in addition to football. But I don't think they're doing that in Foxboro so they might as well as have natural grass. They'll have to ask for help from Green Bay, similar harsh climate so they'll have to find a way to maintain the natural grass in the middle of winter.