So far the X1 will likely reach 30M units LTD in NA going by it's probable sales curve and the 3DS will likely end up selling ~24M units in NA ...
According to NPD, the Switch has had a 20% tracking advantage against the 3DS and it's first month this year also showed a 20% tracking advantage on a weekly basis too so if we extrapolated that the Switch will keep it's 20% tracking advantage it will likely reach ~29M units in NA ...
The battle between the Switch and the X1 in NA is more competitive than what most people on either side of the argument would give it credit for so neither side has it in the bag ...
When Switch and 3DS were about even on a global basis and Nintendo's forecast for the fiscal year was 10m, you projected that Switch won't beat 3DS lifetime sales despite people making you aware that Switch is pulling off the same numbers without a price cut and that it's to be expected that Nintendo will raise their forecast.
Now you make the same mistake by assuming that Switch will merely maintain its advantage over the 3DS in the USA instead of going with the more logical outcome that Switch will continue to widen the gap. In the coming months Switch won't only beat the 3DS by 20%, but by notably bigger margins.
EDIT: 3DS in 2012. NPD data, unless otherwise noted.
Feb - 262k
Mar - ~250k (VGC estimate, NPD thread not properly updated)
Apr - 125k
May - 114k
Jun - 155k
Jul - ~150k (estimate, no clear NPD data)
Aug - 176k (3DS XL launch month)
Sep - ~270k (VGC estimate)
Oct - 192k (minimum value based on calculations)
Nov - 540k
Dec - 1.25m
Most of those figures aren't hard to beat by a margin of more than 20%.
Last edited by RolStoppable - on 10 March 2018