The price of the game covers the 6 decks. Those kind of stretch goals often require setting the pledge price higher and then stripping stuff out. We wanted to include everything essential if we reach the base funding goal. Other thing to consider is the chosen compact box size which can’t really hold any more cards.
That being said there are additional decks in the works, but they aren't going to be included in this campaign. We would love to start working on the expansion decks after this campaign, if it proves to be succeesful.