Voltorb Flip is actually pretty easy to get the hang of and a little addicting if you do it enough.
Yeah, there's a slim chance that we'll see slots and the roulette back (), but they'll probably just add in some new minigame. They should bring back those fun little minigames from Mossdeep/Two Island(?) in FrLg though(multiplayer included) with the usual single playered risk ones, or some new ones all together. As long as there's a variety of minigames, it should still be fun. Then maybe we wouldn't really need to buy coins(as nice as it would be).