My problem with solution 9 - spoiler

[Evergrey]

It really makes you feel like you come from renaissance faire or something and makes a lot of the medieval fantasy concepts look silly. It's very immersion breaking. I'm glad some people like it but to me it doesn't feel like it blends with the world very well.

I felt the same thing with Garleans and the high tech they used.
Never played a FF title before, Magitech just didn't fit into a Medieval Fantasy look to me.
But, I got used to it more and more.
Still not completely though, but I don't really think about it.

And FF lost the immersion long ago with all the collaborations and silly outfits, etc.
So a high tech "invasion" won't really budge my sense of immersion anymore. Because there is none.
FFXIV is to me now just a game to be played for enjoyment, not to get immersed in.