I'm torn on this idea. I love Obi-Wan, and I love Ewan McGregor in the role, but I feel the character has a complete story as it stands, and I don't know that those "missing years" need exploring.
But, "OH GODZILLA! WHAT TERRIBLE LANGUAGE!", if somebody has a story they want to tell, then they should tell it.
Tokyo, a smoldering memorial to the unknown, an unknown which at this very moment still prevails and could at any time lash out with its terrible destruction anywhere else in the world.