Nintendo has two BIG obstacles to overcome if they want Switch to really go that far: competition and system sellers.
We have no idea how people are going to react and transition to next gen.
Last time, transition was faster than some believed. But now, it's still too soon to know how this will go.
Maybe these new consoles will be even more attractive than we think, after they are 100% revealed.
Nintendo has sold more than 53 million based on a few important factors: portability and quality/quantity of 1st party games.
Whilst portability won't go away, the quantity of 1st party system sellers, might.
Most, if not all, Nintendo system sellers are already out. And even if sequels are released, it is not common for sequels to have the same impact or even sell as much as the original titles.
So, the question is: on a system that heavily relies on Nintendo's own games, can Nintendo bring new titles that can carry the console onward - specially when new consoles are arriving? Consoles like Gamecube, Wii and Wii U show that this is not the case.
This is also ignoring a couple of factors.
* Evergreens are system sellers - Games like MK and BotW has actually increased years after they release by year. They will keep selling systems for the reminder of Switch's lifespan.
* Nintendo has one system rolling these days, comparing it to other generations when Nintendo had 2-3 systems producing games for doesnt make much sense.
* Not sure why questioning Nintendos ability to put out quality first party games is even a thing? They're gonna keep putting out quality software.
* Switch doesnt offer the same thing as PS and Xbox which is why a new generation wont affect sales for the Switch. There's been multiple reports from NPD about Switch not replacing any other system but rather being an addition. That will continue to be true for next gen as well.
* Price cut. Switch has had no price cuts and is currently in it's 4th fiscal year. It's when the time comes going to be a way of keep pushing hardware.
Remember the 3Ds were supposed to exceed 100m but in the end they didn't make it.
No one in their right mind actually thought that the 3DS would exceed 100M 3+ years in to it's lifespan. So not sure why you are making this stuff up.