Snap should disappear with the next big Dashboard update, which emphasizes performance and a redesigned Guide that fulfills some Snap tasks (such as background music controls). It doesn't mean that simultaneous on-screen apps will never come back, though. Now that the Xbox One and Windows 10 PCs can sometimes run the same software, there's a strong incentive to run games and more functional apps at the same time. It may just be a question of how you run them.