A Switch "failure" will mean both Nintendo's console and portable divisions have failed them and as such is pretty much game over for their hardware days I think. I mean yes, financially they could make more hardware but you're talking about 3/4 consoles (75% of the time) disappointing and your portable division going down the toilet, I think Nintendo would in that case just focus on other things.
Never say never, but I don't think even they can fuck up that badly, 40 million at minimum should be obtainable. I could be wrong though.







