Nintendo lowballed FY 2017 and overshot their goal. If the same market analysts at Nintendo are making these predictions, I think they'll hit it. There's a lot we don't know about Nintendo's 2nd half of 2018 and first 3 months of 2019.
But I can see both ways, expecting 18 million more Switch units in 9 months is a bit strange. I don't know if they're giving too much credit to Lets Go or what. Analysts are expecting Switch to be the best selling device for the year so Nintendo isn't necessarily alone when they are making these predictions.
I doubted Nintendo the last time that they made the claim of 16M units shipped, and that didn't turn out well for me. I'm hopeful that they do but as of now, it's headache inducing for sure how they'll do it. Let's Go isn't even a real mainline Pokemon game...maybe that helps or hurts their bottom line.
Well Nintendo had overestimated their shipments for 3DS and WiiU several times and even with multiple down revisions...
For the topic in hand I think it will be quite hard to do 20M. And comparing to Wii that probably had the low Q1 due to shortages isn't much parameter on my opinion and even if we use it and instead of just taking 500k of the total make it proportional we see that 18M would be more reasonable to expect.
Wii was not having shortages in the middle of 2009. The reason Q1 had a low shipment number is because Nintendo over-shipped in the previous quarter: They went from 5.43M in Q4 FY 2008 to 2.23M in Q1 FY 2009.