Jeez, I'm sure glad Polygon (and some in this thread) aren't running my business.
The 3DS won't be replaced 1. until it stops selling, 2. Switch installbase is at least a big chunk of what the 3DS has.
Until then, Nintendo will, and should, support the 3DS robustly. Might it cost the Switch some games? Maybe, but doubtful. But even if it were, it's still not an excuse to stop selling a product and games that must have incredible margins.
Nonetheless, the 3DS is still the platform that will receive the updated Radiant Historia, and that's awesome.
I would be happy if SquareEnix would finally announce FFV remake on 3DS but save FFVI for Switch.