135m is obviously not going to happen. No point in even arguing about that.
165m is not going to happen...unless they have a new model and price cuts planned and aren't planning on Switch 2 until like holiday 2025. But that's extremely unlikely.
Probably 90% chance it ends up between 145m and 155m.
It should be right around 140m by end of 2023 and Switch 2 won't even have launched yet, hell it may not even be announced yet at that point. So I'd say 145m is worst case scenario. 145m would be Switch 2 coming out March 2024 and Nintendo stopping production by like end of 2025.
150m - 155m is Switch 2 coming out late Spring 2024 or holiday 2024. Most likely scenario. Figure 140m by end of 2023. Announce Switch 2 just after the holidays for like May 2024 release, Switch still probably sells 6 million in 2024 and then a few more million the next couple years in its retirement. Or Switch 2 release holiday 2024, allowing Switch to get to close to 150m by end of 2024, then sells a few more million the next couple years in retirement.
Probably only chance to beat PS2 would be if Switch 2 doesn't come out until Spring 2025. And like I said above, only chance at 165m would be if they have some major, but completely doable, things planned to extend Switch life an extra year or so and keep sales stronger.
Nintendo probably doesn't care about going after PS2's record though, they care about quarterly and yearly profits and setting up a good transition to the successor. Switch will still be strong in 2023, but will be fading to just decent sales in 2024. Makes sense to bring out the successor in the year that Switch starts heading towards just decent sales. And probably not wait until the end of that year. I would expect sales to be only like 2mil per quarter in 2024 before the holidays. So it would make sense to launch successor second quarter of that year, allowing the final big Switch games to still get precedence through the start of 2024, also by launching in the 2nd quarter of the calendar year it lets them not cut off Switch sales in its final holiday season by announcing Switch 2 before that.
So I'd say Switch sells 140m through 2023, Switch 2 announced Jan 2024, Switch 2 released May or June 2024 just as kids are going on summer break with Switch at like 143m by the Switch 2 launch date, Switch still sells a few million holiday 2024 and is close to 150m end of 2024. Switch ends up a couple million shy of the DS later on once production is ended.