I tried to do some very rough maths to see what impact Smash and Pokemon should have to make these 20 millions possible.
According to vg chartz:
So now if we multiply Switch regular months sales by the number of regular months it's:
888'000 * 9 = 7'992'000 Units, We can say 8'000'000. I counted from April 2018 to September 2018 (6 months) and from January 2019 to March 2019 (3 months, end of FY 2018)
Let's say we add 1 milion of uncertainty, the total sale for 9 regular months is 9'000'000 Units. (1'000'000/month)
Soooooo it leaves 11'000'000 units to sale in three holiday months, 3'666'666/month (October/november/december). it's more or less 4'000'000 units more than last holiday season
It represents a 60% increase compared to last year's holiday. I'm talking about sold through and not shipped.
Do yo think Smash and pokemon will be able to move this amount of systems? I think it could be very difficult to reach the target
I think your calculations are off for the upcoming months. You said it yourself that the 880k per month figure comes from months without any bigger release, the best Switch had in a month before June this year was either one medium seller with Kirby or 2 remaster with Donkey Kong and Hyrule Warriors. January to May was a real drought for the Switch.
June is already shaping up to be a much better month for Nintendo due to getting lots of great games and not just one to keep the baseline going. July also has some great releases, though less than June because many of them were originally meant to release in July. August is a bit weak so far, and September is the month with the sports game releases, so that alone will push sales already.
What is however the biggest shortcoming of your calculation is that it does not acknowledge the boost in sales Switch will definitely have early next year after the 1-2 punch of Smash and Pokémon, plus whatever game may release in that time (maybe fire Emblem? Yoshi? Or something yet unknown? Time will tell).
So basically, you could increase the monthly rate higher than your 880k because it does not acknowledge what we already know about to come. At the same moment, Smash and Pokémon will lead to a, ehm, smashing holiday season with sales well above last year.
All that's missing is some promotional action like a pricecut or, more probable, a black Friday deal to fill up the gap to the 18-20M
The Nintendo eShop rating Thread: http://gamrconnect.vgchartz.com/thread.php?id=237454