Even though the 60'6" has remained the same since 1893, the distance between the average of pitchers' release points and home plate has decreased because pitchers have gotten, on average, taller and longer-limbed. And the decrease over the past, say, 50 years has been significant. (For the same reason, there's also been an effective increase in the height of the mound.) I've seen some estimates, but I can't recall them right now. Nonetheless, I think it's more likely that the effort to produce the same effect will be made by increasing the number of pitches thrown by a pitcher, for example by limiting the number of pitchers used in a game or the number of pitchers on the 26-man roster.
Other sports have been much more willing to change basic rules to improve the game: pro football has moved the goalposts, changed the extra-point and kickoff rules, added overtime, and protected quarterbacks and receivers. Basketball introduced the 3-point field goal, widened the lanes and banned zone defenses. Leagues in other sports haven't held their rules as sacrosanct as MLB.
It's not practical for them to change the size of their standardized playing surfaces. There have been some suggestions to raise the baskets, and there's been some experimentation with that. At least some of those showed a drop in outside shooting accuracy and an increase in rebounding and the proportion of scoring by big guys -- not the desired effect.
Beats me, I dunno.
It's my hope that teams get back to a slashing style of play...putting pressure on the defense, more balls in play. I don't know what analytics and metrics would lead a team to believe that's a good idea but it's nice to think about.
It's the one reason I did like the runner on 2nd to start extra innings. Forced teams to play small ball, move a runner over, etc.