Guild Wars 2

Can I transfer the guild upgrade from one server to another?
If not, will it happen in the future?

Currently no. I have not seen any mention of that feature being implemented in the future but I will leave a dev to speak about that if they chose to do so. If it does happen, it would be a gem shop item.

Regardless of how much it would end up costing, I am sure they would sell as you could have the entire guild contribute to the cost.