That assumes people would buy games at the same rate as they do physical by forcing everyone to digital. It's a big risk and Nintendo don't do risks unless they have no choice.
Well get ready for it because it's likely going to be happening. I don't think PS6 and XBox Next will have physical games, and Nintendo has more incentive to go digital than even they do as cartridges are more expensive to produce than 25 cent Blu-Ray discs are.
Even if say on a 5 million game sell you lose 500k consumers (which I doubt would even happen) who are "physical media or bust", you likely still come out on top profit wise because the $15-$20 extra margin you're making by forcing everyone to buy digital just outweighs any lost sales.