originally this would have been a good idea but we run into one problem which is this:Why would using Maul undermine Rebels? Maul's already been killed several times so he's obviously a cat and I'm sure he can't have gotten through all nine lives yet!
What is this about? I mean Maul is dead so you cant do that story anymore unless you retcon the episode entirely but that make rebels no longer cannon.
this movie would have been fine if Maul hadn't been killed off in rebels but since he is dead we don't have someone for Obi wan to fight. I don't want Obi wan just fighting random criminals but I also want a villain that isn't a rogue jedi or a bounty hunter.
However their are characters who deserve their own movies because they are just cool. so this is how they should handle themI'd wait and see how the Han Solo movie turns out first; wouldn't be at all surprised if that didn't turn out to be an Oceans-type escapade. Think of it like a big-screen version of Zahn's Scoundrels. And it would also be funny because everyone's said VII-IX should have been the Thrawn trilogy so imagine the face-palms if Disney adapted one of his other novels instead! :D
1. for bounty hunters make it like heist movie involving the underworld and shady characters.