Basketball hasn't changed. NFL hasn't changed much, if anything in a direction the viewers don't like. Hockey is the only sport to go through significant changes and it's hard to say that they were for the better.
Baseball is what it is. It doesn't need to retain super high relevance for fans to enjoy it. I think trying to twist the game into something else in order to land new viewers won't really work and they risk turning off the fans they already have.
The only issue is that if baseball really falls off hard, players better be ready for pay cuts.