Xbox One would have sold only 500k units if PS4 would be available. Everyone I know bought an Xbox One but they all wanted a PS4. They said "well, can buy the PS4 only in a month or two so let me pay more than 700 Euro for an Xbox One and few games +Live +second controller instead.
Just yesterday a friend of mine wrote me with his Xbox One
" Kauf Dir mal eine One dann können wir die alte Truppe wiederherstellen "
He even tries to convince me to buy one as well now because otherwise he feels very bad about his purchase.