I can't help thinking that the problem with this approach as a sustainable one is that it doesn't actually seem to be very sustainable. If you are, indeed, still around in five years - and still using the same pricing model - you'll have produced 60 buyable stories with a combined cost of $600. That's an awful lot of money, and new players clicking into the fate page are going to see an increasingly large amount of content walled off to them which experienced players are going to have ended up with for up to $180 less. As a player that started in June it does feel a bit like I've been penalised for no real reason for not being able to buy one story for its original price, but when it's 60 stories instead I suspect that Fate page is going to start looking more and more like a middle finger to new players, and a fair number of them will end up not investing time or money in the game at all. Pricing at 25-30 Fate would solve this problem and probably make you more money, so making it cost much more seems like literally everyone involved in the process ends up being worse off.