People who have no experience doing sysadm shouldn't really comment about how easy or cheap it is to move to the cloud. You do realize that cloud isn't actual clouds right? They cost money, a lot of money. Azure/AWS is expensive, Azure more expensive than AWS but AWS over-complicates everything so good luck not accidentally triggering something that'll cost you thousands in literally minutes. (sorry, personal rant here)

To meme it a little... One does not simply migrate their game over to a different architecture. You can't mix onprem and cloud so easily. Migrating to "the cloud" can take years. I'm not kidding when I say it's not a matter of copy and paste.

Yoshi P. already released a few statements regarding the situation dating back way before the WoW exodus. Again, after the exodus, another statement was made. And again in the past few days. THEY KNEW what would happen and they did all they could to buy new servers to no avail.

People expect things to "just work" in 2021 even though that's unrealistic. That's not how life works. People should have learned their lesson by now, it's been 2 years since the bizzaro world covid hit and yet "everything can be magically perfect".

But to go back to OP's question... It's like if you developed a game for PC but need it for a Mac, or the Playstation. They are different architectures and made differently. You would have to change how the game server functions and how the client interacts with the game server entirely. It just doesn't work unfortunately and all we can do is hope we have a short queue and don't get kicked. The limited availability of servers have punished us all and it's by no fault Square Enix. FF14 started development around 2004 I believe, it's been a long time.