As a fellow NIN player with a lot of experience, I too am feeling the pain from this. Taking a job with the mobility and flexibility it currently has and turning it into something that has to spam gapcloser GCDs to play optimally, but can also end up losing damage from doing so with current potencies, seems like a complete turnaround of job/rotation identity, not identical to but certainly comparable to how Tsubame's fixed 60s CD as a GCD for Samurai turned them from a Shinten-spamming machine into a job with a fixed looping rotation every minute because, optimally, Tsubame would never drift and the entire rotation was built around that.

I can see many of the fixes you put forward being viable, though removing the forced gapclosing from the Raiju skills doesn't change anything if we still need to be in melee range for 2 GCDs after Raiton in order to use them. One possible remedy I can see is turning both forked Raiju and Fleeting Raiju into oGCDs that can be used under a stack of something like Summoner's Further Ruin but from Raiton. So you'd Raiton to gain a buff to use Forked, which would give you a buff allowing you to use Fleeting. At their current potencies as GCDs, as well as current Ninki gain as you said, they're barely worth using and the same goes for Phantom.

60s Huton also doesn't make sense as a change for me. It's been 70s since the job released, and shortening it does nothing but hurt us in fights with long cutscene-style downtime segments like E1S, E8S and TEA, where we can currently carry Huton through the transition but would be unable to do so if the maximum duration was reduced to 60s as is currently planned. Huraijin as a button seems like a patch for the Huton duration decrease and nothing else, If Huton was kept at 70s I can't think of any situations where I would choose to use Huraijin over an Armour Crush combo.

I can only hope that some of these additions to the job are re-considered before release, or at least as soon after release as is comfortable. If they go live with what's currently planned, even if Phantom and Raiju potencies are adjusted so that they can't be a loss to use over a regular combo finisher, I simply can't see myself enjoying this iteration of the job compared to how I enjoyed the Stormblood version or either of the Shadowbringers (5.0 and 5.1+) versions, and might end up having to change to another job once the first tier becomes available since no matter how much I like NIN as it is now I'd prefer not to raid on something that uses 4-6 gapclosers every minute at fixed times and likely die to mechanics as a result of that.