There are so many factors influencing what the final tally will be it's very hard to predict.
How long will the Switch keep selling, especially lite model?
When will Switch2 launch?
Will Switch2 have a global launch or will 'Other' markets get a delay and if so, how long?
What will be the new pricing structure going forward (both HW & SW)?
Will there be a budget revision (Switch mini)?
For how long will there be first party releases for current Switch?
But I'm going for a guess, that yes eventually Switch will reach 160Million, because I'm guessing it will be on sale somewhere still for the next 5 years. Probably not in all territories for that long for sure. I'm thinking on how the Famicom kept on selling long after successors had come to market.