I think 10-20 million pre-orders in the first 24 hours is reasonable. And they may yet reserve some inventory for retail channels. Not much, but some. They are least going to want demo units in the stores from Nov. 3.My gut estimation:
I have to imagine that the smartphone market is pretty well saturated by now.
I can't imagine iphone 7 sales to be a lot higher than the 6S. Say 15M max.
With high market saturation, pent up demand for something new, but higher prices, the demand for the X should roughly equal the 7.
I'd say 15M on opening weekend.
I can't imagine it'll be too difficult to secure a phone at 12am on launch day.
But yes, with 12 million ready to go, and 10 million allocated for day-1 pre-orders...I'd say it will take a few hours for that to sell out entirely.