In the press interview, it's already confirmed by Yoshi P that there is a completed system for cross-region data center travel that works, they just want to wait a little while longer before choosing to implement it or not.
They're really hesitant to, and haven't gathered enough data with players yet (likely opinions that is favourable to the feature), so they need to wait longer.
I'm gonna guess that they're waiting until 6.5 before they make the big decision and then will implement it during 6.58 during the really long content lull, because it will definitely get players to resub and see how the experience is with cross-region data center travel.
However, their second plan is to create a system where it's cross-region matchmaking for instance content, but it seems it's difficult with making it work with the spaghetti code. But if they do make this work, then they're most likely scrapping cross-region data center travel, and will implement this instead to avoid a huge culture clash. It will definitely be a good feature to have for Dynamis and Materia data center.
So this can go either two ways (or maybe three):
1. They fail to make a system for cross-region matchmaking, and will have to implement cross-region data center travel, thus we will see the shitstorm of culture clash.
2. They successfully create a system for cross-region matchmaking, and will no longer implement cross-region data center travel, which is still good and the best case scenario for this game and its playerbase.
3. They fail to make cross-region matchmaking, choose to miqo'te out and NOT implement cross-region data center travel, and Materia and Dynamis are doomed in the future.
If they manage to do either option 1 or 2, I'm definitely going back to Materia which is my local region. I do think they should pick with either. But definitely not option 3. That would suck.
6.58 is the perfect time to do it. We're really bored. And the culture clash would probably give us amazing drama that FFXIV players just thirst for. It will be fun. And the drama probably won't even be bad. You guys are just amazing at losing your minds over the little things.