If Nintendo could hold at 70 million portables for next gen, that would be OK. Probably not ideal, but OK at least.
But I don't think they can, the 3DS is really sputtering badly here particularly in the US where it still manages a mediocre sub-100k/month quite often even when a new model revision just recently released. I think it was able to benefit a lot by having that large surge of sales early in its life cycle before mobile had really cemented itself with younger kids.
Because circa 2011, the iPad was still extremely expensive, you couldn't just get a tablet for $150 like you can from anywhere today. Also when mommy/daddy are upgrading their phones/tablets nowadays, guess who's getting the older one in many cases ... the kids. So that problem has exasperated itself.
Flying a lot for work, nowadays I notice with families a lot of the kids have their own individual tablet now, back in 2011, I don't think that was the case. Seeing a kid with a 3DS is exceptionally rare these days, and if you see one, there's like 10 other kids that aren't gaming on a 3DS.
If Nintendo can manage 50-60 million handhelds next cycle, I think even that will be really good considering the circumstances, a minor miracle even.
