There were talks around 10 years ago. Emma Thompson was attached to write the screenplay and Carey Mulligan was going to play Eliza, but it went nowhere.
https://www.playbill.com/article/cameron-mackintosh-says-film-remake-of-my-fair-lady-has-been-shelved-com-217967
This is a cash-cow title for Disney so it has a better chance of a UHD release than a lot of other titles in the catalogue. From what I've heard, Disney plans to release future UHD titles on a case-by-case basis.