I don't baseball supplanting the popularity of the NFL any time soon. Most people don't care about football players getting concussions. At least not enough to stop watching football. Probably not in the very near term, but if the NFL doesn't do something substantive about player safety, it's going to bite them hard before long. It's becoming a more visible issue, players are expressing regrets over choosing the wrong sport, and we may well see the tide turn when it comes to athletes choosing football before baseball. There's a long way to go before we can talk about MLB supplanting the NFL, but it's entirely possible we've reached the zenith of football's popularity. I think the concern about safety is a facade more than anything. Many of the same people who whine about the NFL also actively support UFC type events which are far worse for your health. Baseball is still slow and lacks flash. When I was a kid, long before the concussion issue, there were plenty of parents that didn't allow talented kids to play football but it just opened up spots for other kids. The bigger threat to participation may be a growing Tea Party hacking apart public school budgets and making it impossible for high schools to field teams.