Worst case scenario-100 million
Best Case scenario - 150 million
My prediction- 120 million. I expect the system to peak in 2020(Maybe 2019 depending on what's releasing that year.) The combined support of both handheld and home console ecosystems will help the Switch a lot. It has a monopoly on Handheld gaming. (Something a Nintendo handheld has never had). Plus a revived home console market. I expect it to do well.