Oddly, weird as people think this request is. They have done this in the past. So they may do this for EU servers at the very least.

Back during Stormblood, you'd get a one hour warning that servers were going to reboot, thus everyone was put back into a queue once more. This was on the Japan servers at least.

https://na.finalfantasyxiv.com/lodestone/news/detail/263f9a10fe534e8c93e43d08fde73eaba1c52976