What I'd like to understand is: who that hasn't already bought the Switch for Pokemon, Mario, Zelda and other franchises has not already done so? It's at 122M and at a high price.
Without a new SKU, how could it reach 160M? Yes TotG will be huge and ignite excitement, as would Prime 4 and the upcoming new Mario, but most interested would already own one.
And like some have said, the Switch seems to not be like a DS where there could be many sold per houseold except in rare cases. It seems like there may be a cap somewhere.
Still like was said earier regardless of its final HW sales numbers, it will have generated massive HW and SW profits.
A too big emphasis here is put on HW sales, but what Nintendo can do with the Switch is use it as a money-making machine by pumping out more great games and selling them to the 125M+ already owned consoles. That makes the most sense to me, and so a drop in HW sales should not warrant the announcement of their successor, rather a drop in SW sales should be used as the litmus test.