I love the boldness. I think you're right about how high it will peak over the next couple years and I've agreed for a while that Nintendo plans to give this system more longevity than usual, but I also believe once Nintendo does start to look beyond it (2024-2025) sales will tail off fairly quickly, similar to the PS4 right now. Can't see it adding over 30m units in 2025+.
I'll say it sneaks over 160m, maybe gets to within ~170m, but I won't go any higher than that for now.
Think that puts me roughly on track. Haven't cracked any real numbers so it's just a general guesstimate.