In my opinion MNK doesn't need a complete rework. Little changes over the course of the expansion would be fine. In patch 5.05 the big 2(3) I wanna see are:

1) Make Tornado Kick function like Foul. Maintain GL for x amount of seconds and you proc TK. This makes it rewarding to maintain GL which they are HEAVILY emphasizing in this expansion and allows us to use our most potent ability (since, ya'know, we're literally the ONLY job in the game whose most powerful move is situational and not just part of the rotation). Additionally, make 6SS an oGCD that when used triggers the GCD. Honestly, I'm fine with it being the downtime skill if TK gets reworked. Especially if it's an oGCD, it'll be simple to weave it in before re-positioning.

2) Give Anatman an instant tick. That's all it needs, and yeah give SAMs an instant tick on Meditation as well, idc. Having to wait for that Anatman tick in the opener is so annoying and just makes the job feel incredibly slow.

BONUS: 3) I would be fine with or without this change in 5.05, but if they gave us another oGCD to use I'd be very happy. Personally, I want One Ilm Punch to come back as an oGCD on a 60 second CD with a potency of 300 or something. A nice hard-hitting oGCD to weave every minute and would align with every raid buff (just not always RoF and BH unless they rework those to be RoF - 60 second CD, 10-15% damage buff, no slowdown. BH - 120 second CD, 50% chance to proc chakra instead of 30%).