^This would be the main problem, not the cost to realm transfer (which can be done with gold).
The other problem would be why don’t more players want to run mythics? If more players wanted to do the content, you wouldn’t have a problem putting groups together. Are the raids too difficult? Not rewarding enough? What incentives would get players who don’t raid, raiding? If you have ideas on how to solve that issue, I’m sure Blizzard would like to hear them.