I think the winner in the NFL implosion is likely to be Major League Baseball.
And Hockey!
In the last few years, I've abandoned the NFL (I abandoned the NBA long ago ...) and have migrated towards MLB and increased my NHL viewing. I'm a big Chicago Blackhawks fan (have been for decades) and started watching more and more baseball over the past two years as well.
I started watching baseball again two years ago, having given it up after the second MLB strike in the early 2000's. Started watching again when the Cubs were on the uptick and have really enjoyed MLB again and fell back in love with the game.
The NBA and NFL can kiss my lilly white ass far as I'm concerned.
NFL and NBA will lose fans, but I don't think MLB will gain very many. It's still too slow-paced and requires too much intelligence for typical short-attention-span fans of other sports to get into. It seems to me that you either grow up with baseball or you never really get it.