Regarding what you say about the longevity of the game, it is something that is true and can take its toll if they don't do something to keep the community hooked.
Personally I see this new expansion of new cards, as something normal, I do not see that it will influence much, although it is good to follow closely these new cards, it is not known how they can influence the competitive mode.
I feel that the combat mode is fine even if the card cycling sometimes feels fucking unfair. But even so the strategy that is implemented is the one that ends up predominating in the game, knowing the current deck goals and cards gives us a plus to overcome the difficult moments in the combats.