It was inevitable from a game development POV, once portable graphics go past rudimentary N64 to Dreamcast tier visuals, the amount of resources the portable line would require is basically the same as a console.
And no company can support basically two console lines. And you saw that with Wii U and 3DS, Nintendo had massive problems getting games out for both at a regular rate. Ditto for Sony with Vita and PS4.
And "3DS-2" would've presumably been another generational leap making things essentially impossible.
Yep, if Nintendo continued with the separate handheld and console line than it would likely be a $199-249 Vita+ level handheld and a $299-349 XBO/PS4 level console which would just make the problem worse.
Things like cross buy/play/save that we saw on some Vita/PS4 games could help the situation but it wouldnt be enough.
When the herd loses its way, the shepard must kill the bull that leads them astray.