Making two separate systems, one home console and one portable, just wasn't viable any more, even with Wii U and 3DS they weren't able to produce enough software for both.
A powerful new console and a next gen portable would've been even worse, and there's no way they'd give up their portable line and go all in on a home console alone when historically their portables have always sold more.
Unifying their product lines, as they did with Switch, was really the only viable path forwards.








