To note, the 3DS gets a pricecut sometime in the summer in the same time frame (I remember August). That's when things will get interesting. Switch is doing great so far but I'm not sure it will get to the heights of the 3DS during its first 3 years.
Note first year 3DS it sold 4.3 million with almost 1.6 million units sold in December that year after 3D Land, MK7 and MH hit in the holidays. If the Switch can sell 3 million I think it does an excellent job.