Arkaign on 16 August 2014
I guess I kind of got sidetracked there, TLDR :
I think PS4 could very well sell 18M *IF* they could produce that many for the high demand weeks. That's doubtful though.
Long-term, this gen will surprise people. Most customers buy in when the prices are better, and $399 is too much for the majority of the market. Sales will open up like a floodgate at $299 and under, and WiiU will get a solid second wind at $199.
