It’s not going to happen, at least not anytime soon. As the rumor goes, Lucas made it part of his contractual agreement with Disney that the theatrical cuts were not to be released (we know how badly he felt about the special editions being the “only” editions). Even if the rumor isn’t true, the next best theory that I can think of is that, even though Lucas is retired, he still has friends at LucasFilm who likely want to respect his wishes. People forget that LucasFilm has control over Star Wars, not Disney proper. Disney has a history of letting their subsidiaries do their own thing for the most part (same with Pixar, Marvel, etc).