World of Warcraft, but the game has never had an actual in-game store. You've had pets and mounts that toe the line, but the line still existed. Then a bit of datamining turned up an experience boosting item that looked as if it might be tied to an in-game store. But datamining isn't the same as actual confirmation, and thus much nervous hand-wringing ensued... until community representative Zarhym confirmed that yep, this is a thing that is happening.
Zarhym's posts specifically state that Blizzard is "exploring the possibility" rather than definitely adding a microtransaction store, but it seems the most likely outcome. Maybe not today, maybe not tomorrow, but sooner rather than later. No word on what this means for the future of the game's business model or how much will change from the game's current system with an online storefront, but it's certainly surprising to see one of the last games without an in-game store taking steps toward adding one.