I don't think this is true at all..for that to happen x1 would have to start outselling ps4, and as far as I know it's not happened. Didn't sony say ps4 was #1 in UK first 6 months this year? Doubt that will change.,
I think it can happen. Suppose Previously PS4 sold 130 and XB1 sold 100
so the ratio will be PS4 1.3 : 1 XBI
Now this year PS4 sold 105 and XB1 sold 100
Total will be 235:200
which will be
PS4 1.17 : 1 XB1..
So PS4 still won this year but with a much smaller margin.. Which will keep all the statements true.