I don't think Planescape is too controversial to be published by any means. I use alignment for Planescape, just not for characters. Dark Sun has some touchy subjects in it, but so does Ravenloft, so I think the likelihood of it getting published is nearly fully dependent on 5e having better psionic rules instead of the iffy stuff with the brutality of the world (slavery, cannibalism, etc). Oriental Adventures is never going to be published in 5e, at least not in that name and definitely in a different shape. If they were to do some kind of "Oriental Adventures"-ish content, it's likely going to be scattered through sourcebooks like the Samurai and Kensei subclasses in XGtE, be a M:tG setting book, and/or just be Anime-inspired subclasses/race (like the Astral Self monk).