Whoever is right 1.6 or 2.5 million or whatever, could in this case be of lesser interest compared to showing the slow shift towards a tablet replacing the laptop for many casual users.
When the price drops so it can compete with a laptop, we can overtime experience laptops disappearing from the market.
I know we are talking many years here, but in time I think it will eventually. The surface is showing the way forward in this respect. Suddenly printing is no additional acrobatic feature but integrated and you can do your spreadsheet- and report-work as you would on a laptop.
The fact that it is still pricey to configure it to replace the laptop is also of lesser importance as the price will drop over time when other competitive products enters the market.
Right now, I must say I find Surface 4 rather tempting, but the configuration I would like makes me hesitate due to the pricetag.