GameXplain confirmed the new feature and the fact that it doesn't support other USB controllers before testing it out by playing Fire Emblem Warriors. By the looks of things, you'll have to get used to playing with a completely different layout and will have to accept that you'll lose access to certain features if you use the GameCube controller alone. But if you want to challenge yourself in a new way or to get a taste of the old days, then this sounds like a great feature to take advantage of.