It was announced at the end of 2019 that as part of Sony’s extended agreement for the MLB license, the series would no longer be exclusive to PlayStation, and would be coming to Xbox and Nintendo platforms as well.
MLB The Show 21’s target platforms haven’t been officially announced yet (and you’ll notice that a Nintendo Switch box art hasn’t leaked either), but the game’s going to be officially unveiled in February, so we’ll probably learn more about it soon.