1.688.426 + at least 652.614 from digital sales = 2.341.040.
Add additional digital sales and it might be around 2.6m right now. 3m is not a minimum, rather a maximum threshold unless the game has big legs. For reference, MH4 sold 4.1m in Japan and MHX is well above 3m.
? Game sold 159K last week. Even with a pessimist 50% drop expectation, that's another almost 80K, and retail will be 1.83 million. There is no way retail sell less than 2 million, and digital should pass 1 million with 650K only first week.
3.5 million is possible, maybe less but there is no way 3 million is the maximum. 3 million is guaranteed right now.
EDIT: I use MC retail sales