I’ve spent a couple of weeks in Japan some years ago. I saw Nintendo 3DS all over the place, those were everywhere. Everywhere. I saw only two PS Vita.
Japan has a good niche market for the handheld due to the constant train/subway commuting. The console mobility, added with strong JRPG titles, will mean the Switch is possibly THE winning console in Japan for this generation.
Maybe Nintendo focus on Japan on the console platform market from now on?
Switch is not just gaining the development pipelines of 3DS and Wii U (though Wii U was arguably Nintendo only). Switch will be gaining the development pipeline of Vita too. Switch is Vita 2. There will be no Sony handheld this time around. Those handheld games have to go somewhere.