Nintendo could make it easier to communicate with friends and setup gaming sessions. It isn't big deal for me since if I am going to play Kart or Smash with friends we either text each other first or call. There are definitely areas that need improving. Also the slow pace of VC releases is pretty pathetic. They almost abandoned regular online players focusing on the plus subscribers it seems in my book. There are still tons of NES and SNES games that could be released.
Also they should bring back Nintendo Selects for 20 dollars for some other their older first party games like Yoshi, Kirby, etc.