Nintendo's focus is to leverage its software library to sell its hardware, and to reduce costs of hardware while addressing a wider audience.
The wider audience being referred to here is: Handheld console gamers that are more price sensitive (i.e. impulse buyers, parent's buying their young child a console, etc.)
Simplest solution: a 10nm or 7nm Tegra X1, smaller battery, reduce the entire chassis size, and remove the active cooling, etc. they could probably do it for $199 next year (Late 2019) just in time for the handheld focused Gen 8 Pokemon on Nintendo Switch (again leveraging the right software to sell this smaller size hardware).
A separate system that does not just play Switch games isn't in the cards for Nintendo right now because they are already stretched by doing iOS/Android/Switch games and all their merchandising/movies/themeparks/amiibos/etc. Plus, Nintendo is still needing to expand its First Party Support of the Switch much more than it has this year, and they can't afford to risk splitting third party support either.
They will gradually drop price of the Nintendo Switch and its revisions each year until they cover where the 3DS is now. I imagine they will try to get it down to $129 or $99 by the end of its life if they can (inflation being the biggest possible impedence to that).