It's not going to make baseball as popular nationally as it used to be, but it's still a necessary move, IMO. I've been a baseball fan for 30 years, and grew up with the game, so I can sit through a 4 hour TTO fest and still be entertained by it, but if MLB wants to attract new fans, casual fans, and younger fans, then they need to evolve. Yes, they will also need to market their stars better too, but marketing the stars better without making the games easier to sit through for the average fan won't solve the issue. They need to do both.
As far as the rule changes, I like all of them. Baseball fans are usually the fans who hate change the most, but I think the pitch clock is going to end up being universally loved soon enough. The players are probably going to hate it until they get used to it, but it should help the entertainment value of the game.