160m is very plausible at this point tbh the platform can get well within range of DS and PS2 by the time a successor arrives and then leg its way to 160m, 3DS after all went on to sell a further 10m after Switch launched, it may not even need that however given it's current momentum as a decent year this year and an average one next year can actually see it close in on the milestone.
3DS benefitted in two ways that allowed it to keep selling. The Switch did not play 3DS games and a 3DS model (2DS) was as low as $79 RRP, less than a third of the price of the new console. So a different library and a very different price bracket meaning Switch didn't make the 3ds redundant. Assuming the next console is the Switch 2 and it is BC I expect Switch sales to fall very quickly once it's successor is released. Just like the PS4 I don't believe we'll see a significant price cut for the Switch at the end of it's life, especially while we are currently in an unprecedented situation where console prices are actually being increased and Nintendo will want to strongly push their new hardware as a direct replacement of the Switch.
Assuming no new Switch model, no significant price cut and Switch 2 in Holiday 2024:
End of 2023 = 137m
End of 2024 = 147m
Final Tally = 153m-157m
They absolutely can break the 160m mark if they release a new model, substantially price cut or don't release the successor until 2025 but currently I'm pretty confident none of these three things will happen.
Basically the ball is in Nintendo's court, they could get the Switch to 160m easily, but I believe they'll focus strongly on quick adoption of their new system rather than using promotions to eek out a few more million from the Switch.
We'll at least find out if there's a new model coming in the June direct, I imagine if there is one final hardware revision coming after all that's the date it'll be announced.