Like I said in the other thread 7.5m is my current prediction. I could see them shipping up to 10m. But anything more than that and I'll be questioning if the world is real or if I'm actually in a coma.
Smash Bros has a strong hardcore fanbase, which means it has a lot of early adopters, while having limited legs compared to other Nintendo games such as Mario Kart. So First Year sales will make up the bulk of it's total sales, I.E by the end of 2019 it'll have sold around 75-80% of it's lifetime sales. But even being frontloaded for a Nintendo title, 15m is too much in 24 days.