Nintendo should've done this a year or two ago. I just fear that their mobile titles will all be mediocre half-games, like that weird Pokemon thing they put out on phones, or a lot of the stuff that they've put out on the eShop. Mobile would be perfect for a new WarioWare game, for example, but it'd be even better if they could make a full-fledged Pokemon game for the systems - a new Pokemon Stadium would even be perfect for mobile. My inner businessman quivers at the thought of how they could monetize those franchises. The rest of me hopes that they can find a balance between quality and monetization.
Either way, it seems like a lot of Nintendo's quality teams have been focusing on the Wii U, which I'll actually be kind of sad to see go, and this announcement didn't necessarily give the impression that they'd be too intimately involved in the development of these new mobile games. They have a history of squandering potential, so call me cautiously optimistic at best right now.