I think Nintendo is pretty balanced in terms of catering for kids and adults- but you have to recognize that they are catering towards a pretty light hearted gamer. it's not that they're necessarily after one age brakcet or another, they're simply a game company that wants people to play their games to have fun and hang out with their friends over Mario Party or Smash
if Nintendo were exclusively aiming towards kids they wouldn't have created a lot of their franchises the way they did, into fairly difficult things. no kid under the age of like 9 is going to be able to beat Ocarina of Time or Majora's Mask (well I suppose except a few exceptions) and the same can be extended to other series
something like Mario Kart or Smash Bros. definitely has a giant following from adults
whether its due to nostalgia or not, it just shows that Nintendo strategy works in the sense of they try to get people interested in their games as kids with the hope and expectation that it will flow into adulthood
