The downside to this particular Star Wars theory is that Mark Hamill has aged out of the role of Luke Skywalker in The Mandalorian timeline, though they could utilized the de-aging technology we’ve seen in the MCU and Rogue One.
It’s unlikely that either Luke Skywalker or Mace Windu will show up in The Mandalorian Season 2.
The latest Star Wars fan theory believes Mace Windu landed on his feet and soon after went into hiding, fighting the Empire from the shadows.
Nor that Mark Hamill wants anything else to do with the Star Wars universe after publicly complaining about the fate of Luke Skywalker in The Force Awakens Trilogy.