Cashshop is not a must. We have always follow this rule: A B C D determins a player's power, ABC is free, D is for payment. So D won't interfere the balance of the game
While most players are not willingly to pay, they can enjoy most of the ABC to raise his character strong
And we used to sell only 1 dragonball in conquer online. So we are not that much money driven since we have other products as well, we are gameplay driven