I picked 3-3.5 million. Thinking that the demo + the Switch bump will bring it up to that number, but the series is still pretty niche so don't see it selling much more than that. Pikmin 3 deluxe has the most sales in the series so far with 2.23 million sold, for reference.
I like it when my mom goes out of town because I get to sleep on her side of the bed. -William Montgomery