Well to be honest they should do 1 of 2 if they want to expand the game
Make it free and charge to buy the expanison, kida similiar to gw where you buy the game but dont pay sub fee but have stupid cosmetic microtransations which we already have in a SUB GAME
OR CHarge the sub feee, but make ALL expansions free, someone on a sub 4 months pays for an expansion and alot more people will sub who dont have 60 bucks to pay right off the bat.