The original Dark Souls is not available to purchase on the Xbox Store. But if I already bought the game, I can still play it even after it was already delisted.
You guys remember when Ubisoft said they were delisting Assassin’s Creed Liberation from Steam? Everyone freaked out. But it was such an overreaction. If you already bought the game, it’s yours forever!!!! Even if it’s delisted. And even if you uninstall it, you can choose to install it again because IT’S YOURS.
I used to believe physical copies were the only way to own your games. It’s pretty misleading to think that way.