2020 might catch-up by the end of the Quarter but this year we have OLED, Pokemon, Mario Party, SMT V and a bunch of other games likely to launch in the fall.
Last year it was basically Momotaro, Age of Calamity, Pikmin, as major titles and there weren't that many mid-tier titles either.
End of the year, I expect Switch sales to be closer to 6.5 million