Makes perfect sense. Put simple version of games from their franchises on mobile and rake in an extra billion or so dollars a year. Now that Nintendo doesn't have two systems to support simultaneously (with the 3DS fading away soon), it makes sense to throw some resources at a huge market that they have barely touched so far.
Since Switch already has Mario Kart I could see a mobile Mario Kart coming out in the couple years. If they do the incentives right like Pokemon Go (and not Super Mario Run) they could easily rake in many hundreds of millions from a game like that. Mobile might become their new platform for their smaller handheld line of games. Though certainly most resources should be for Switch. But if they say divert 10% of resources for mobile I think that'd be fine.