From my past experience in playing browser games, I don't believe you can change servers, nor will there ever be an option of that sort available in the future.

Server changes are not likely to happen, but considering the game even comes with a client and its licensed its not impossible to happen, I wouldn't completely rule it out. Especially if a lot of people ask for it and they see that the profit for implementing it is higher than the cost of designing it.

If it would be possible to hop servers for a certain amount of ingots/coupons I am sure a lot of people would make use of it.