If we take baseball at its word, this solution makes no sense to solve that problem.

1) you’re going to increase offense which will increase the lengths of games

2) you’re changing the equilibrium of the game. Why not make all pinch hitters stay in the game after the have a PA?

3) if you want to speed up games, lower the time between innings. Have all plays reviewed so you don’t have teams stall as their replay team investigates if it’s worth a challenge