It`s pretty much a giver sure that XV-2 is coming some point in the future. If I would bet, since the game scenarios, models and engine are pretty much done, I think late 2018 or early 2019.
Why I`m sure XV-2 is coming? Well, this game took 10 years to be complete and huge amount of resources, now the most rational thing to do with is to re-use it assets to the maximum to optimize costs, just like they did with X and XIII. And since this games has no way of generating extended income like GTA V with Online, sure, some DLC are coming too.