I think there's reason to doubt whether or not baseball is really losing any ground.
www.theatlantic.com/entertainment/archive/2014/04/baseball-isnt-in-decline-debunking-the-biggest-4-myths-about-mlb/361070/2/
Myth No. 4: Baseball Is Declining in Popularity
Last fall, in a New York Times article titled “Is The Game Over?” Jonathan Mahler wrote that baseball “has never been healthier. So why does it feel so irrelevant? Maybe the best evidence of this admittedly unscientific observation is the national TV ratings …”
Well, that certainly is unscientific. If the game has never been healthier, why would it matter if national TV ratings were down? Nationally broadcast NFL games routinely outdraw nationally broadcast baseball games by about four to one. But what difference does that make when nearly all baseball fans watch their teams play on local networks?
And, as I wrote last fall, baseball’s appeal is largely regional, while football’s is national. On a given Sunday afternoon or Monday night in the fall, the nation’s football fans will tune in to watch, say, the Dallas Cowboys play the San Francisco Forty-Niners. On a spring or summer night, most baseball fans aren’t watching a national game; they’re watching their team.
It’s no more relevant to argue the greater popularity of pro football by citing national TV ratings than to maintain that baseball is more popular because it outdrew pro football last year in attendance, 74 million to 17.3 million. People consume these two sports in very different ways; that doesn’t make either one of them less of a great American pastime.