Baseball has taken significant steps this season to shorten the game through new features like a clock for pitchers and batters. A growing consensus over recent years has suggested fans want shorter games. College football is considering shortening games. However, in the absence of data I have encountered about what fans actually want, I wonder if it is really about shorter games. These might be two other options that sports fans in America want:

-More action. Studies have shown sports like baseball and football actually do not have much game action across the multiple hour experience. Pitch clocks make the action happen quicker but do not necessarily mean there will be more balls in play or runners on base. Baseball has moved in recent years to more three true outcomes: strikeouts, walks, and home runs. These involve limited action.
-A higher action to time ratio. Perhaps what fans want is not shorter time but more action within the time of the game. Shortening the time with no change to the action would provide a higher ratio. Shortened times plus more action would further increase the ratio. Other sports have more flow or continuous action, like hockey or soccer (though many American fans might consider these action low-stakes or boring action). Or, watching a condensed game where the time between all pitches or all football plays is removed can be an interesting experience.
I suspect there might be plenty of experimentation in the coming years regarding finding formulas for sports in order to retain or attract the attention of fans. This will also happen with ongoing interaction with other forms of entertainment that offer different experiences and timelines.