In Japan I would say this migration is well on the way based on sales. The Switch is massively outselling all other Nintendo handheld variations combined in that country where the handheld is king. 3DS family sales are in fast decline (BUT still relevant).
Switch games dominate the charts more than the old DS family in Japan (and globally come to think of it).
When the biggest Nintendo franchise of all, Pokemon, say goodbye to the DS family you know things are moving on. Fire Emblem and pretty much every other DS game is probably now being planned for the Switch.
Nintendo is a business and its primary goal is to make money and be successful.
If I was the man at Nintendo I would somehow find a way to feed the new kid on the block, the Switch, while at the same time milking some more money from the old daddy, the 3DS/2DS.
I would also want EVERYONE that owns a 3DS to pick up a Switch ASAP. To migrate. I believe they are achieving this.







