On the subject of the Switch reaching 170 units. Regardless of if people underplayed previous Switch Sales, and it's eternal performance in Japan, Switch sales have been dropping in recent years and globally they appear to have slowed a fair bit. Likewise the assumed price drop look likely that it won't happen due to the global economic conditions. Old technology and production costs aren't dropping in price like it did 10-20 years ago.
Also I don't see Nintendo doing a Sony and selling the Switch over the next generation cheaply to poor markets like Brazil like Sony did with the PS2. I agree that 160 million units is reachable, but challenging. I think 10-11 million units will be sold this year at least, hitting 150+ million and it will take two more years of support to hit 160+ million. Nintendo said they'd only support a console 3 years after the next gen is out if I recall so 160 million is a tough target and Nintendo aren't really known for continuing to back their old consoles with support of major games that aren't Pokemon. Perhaps a few more remakes (The remaining 3D Zelda's) can maintain momentum.
Claims about the size of the mobile market is a tad irrelevant. However you categorise the Switch, it's still $350 and the PSP and DS were a 3rd of the price in much better economic times and no mobile markets, social media or steaming for competition.