We're already doing this and the season hasn't even started?
Repeat after me, "It. Won't. Make. A. Difference." The pace of the game is not why people (and by people, I mean the ultra-coveted 18-35 demographic) don't watch. People don't watch because they find the sport, itself, boring. Like the sheer design/purpose of the sport. No amount of time-shrinking is going to make one iota of a difference. If you don't like baseball, you don't like baseball. Bastardizing the rules isn't going to bring in young fans.
I do agree that measures such as eliminating the intentional walk, and other things designed to shave maybe 2 minutes off a game isn't going to move the needle. The issue is that the action is so sparse that it is impossible to hold the attention of a casual fan.
Baseball was always my favorite sport to play/watch growing up. But that's when I had all the time in the world on my hands, and would do homework or play on my GameBoy or something during the dull parts of the game. Now, as most people, I don't have the time for that. I can't blame people that don't want to watch a game where they might not see a ball put in play for 20 minutes, or see a baserunner for over an hour.
At some point the MLB will need to decide if they're fine drifting towards the bottom of the pecking order of the four major sports but keeping their traditions and style of play, or whether they want to make significant changes in order to keep up with the changing interests of fans. Radical changes that make both the games shorter, as well as the time spent playing the game to be more action-packed would definitely be shunned by hardcore baseball traditionalists, but they would almost certainly bring in a new group of fans. Things like starting everyone at 1-1 (which is essentially just lowering the strikes needed to strikeout to 2 and balls to walk to 3), or starting innings with a player on base, would speed up the action and increase scoring.
Obviously the easiest thing to increase action in NL games would be to adopt the DH.