Well, The Artisan Cave was the one found in the Battle Frontier. This is where you find Smeargle. Alterning Cave however, which is the cave in question, was intended to be used as an event area when you use the Mystery Gift function at a Wonder Spot hosted by Nintendo. However none of the events actually ended up being held for either the Alterning Cave in Hoenn, nor the one in Fire Red & Leaf Green. It was intended that you would be able to catch some rare Pokémon in there such as Mareep, Aipom Shuckle, Pineco, Teddiursa, Houndour, Stantler, and of course, Smeargle. This was probably a nod to the game's predecessors Gold, Silver, and Crystal. However all the Pokémon were made available in the extended area of the Safari Zone in Emerald, except for Smeargle in the Artisan Cave.
I suppose that both the Artisan Cave and Alterning Cave were two areas that never really got their intended purpose actually resolved during the release of Emerald. I'm assuming that Alterning Cave will receive a whole new function however, with all the extra features in the games these days it is unlikely that it will simply serve as a small cave to host a few wild Pokémon that you need to go to events for. However, changing the name is something I don't think they will do, so they will need to make the cave dynamic in some way, perhaps being an area where you can change Rotom formes or something similar. Making it a Friend Safari seems a bit random to me, especially since it's a cave. However in Emerald the cave opened up after you beat the Champion, much like the Friend Safari accessibility in X&Y. So that is entirely possible. Though I do imagine that the Friend Safari will have a different location, perhaps in the Battle Frontier. Either that, or they'll remove it completely. Though I'm pretty confident that it won't save the same purpose as it did in Emerald (which essentially ended up being nought but a Zubat hangout).