I don't know if the focus is to shorten the game time as much as it is to make the games flow better. Without a clock, there's simply no way to control how long a game goes, but a 3 hour game with less dead time in between pitches, more action, etc, is a far better entertainment product. That's the goal. The 3 outcomes that the league wants to increase are triples, doubles, and stolen bases. The bigger bases + cap on pick off attempts helps with the SB's, and I would think the shift ban is going to help with the 2B/3B, or at least BABIP. Combine that with a pitch clock, and I think the games should flow better overall. At least until the Rays find a way to exploit the rule changes.
The thing I've noticed watching baseball with casuals/non fans is that the one thing that gets their eyes off the TV screen and onto their phones the fastest is the time in between pitches. The pitch clock is long overdue. If they just did that and kept everything else the same, even that alone would have improved things. I do think the other changes are a positive though. We will see how it looks on the field. I'm guessing there will be an annoying period where there will be excessive balks and automatic balls/strikes due to pitch clock violations. Hopefully that doesn't last long. Most curious to see what the pitch clock does to velocity. I agree, limit the number of pitchers a team can employ and it will make a difference.