3.84 million first month means at least one of tbone's predictions for Zelda (near 4 million first month) have come true, so well done on that.
I'd love to see Breath of the Wild hit 10 million, but personally I'd still expect the game to top out around 7-8 million. However, I'm happy to be proven wrong. This is also the first Zelda title that's going to receive DLC support, and while that might be limited to two packs this year, it's not inconceivable Nintendo will launch further DLC for the title in the future. If they go so far as to offer a major expansion - and sell a 'Game of the Year' edition - then perhaps that's where Zelda's 10 million comes from. It'll certainly be interesting to find out.