Without actually looking too much into it, I could see the Wii overtaking the PS4 in NA+EU due to the humungous holiday bumps the Wii had. I think we'll see a constant fight in all the other quarters, though.

I'll answer for Europe + America, both because that's the simple way to find the data needed, and because that's the reliable data. In a sense, it's also the fair comparison, because you're comparing the markets that have stayed the same, and ignoring both the expanding markets (rest of the world) and the contracting market (Japan).

With Europe + America, the answer is very simple.  The Wii will definitely overtake the Ps4 in both.

Here are the amount the two had sold after certain increments of time, in the USA.

 Note: For both, 11 months is 1 week short of 11 months. Oh, yes, and all numbers are in thousands in all the tables.

This might be a bit tricky to read, so to help, here's the data for how much they'd sold per month between those points, still in USA alone.

 It's easy to see here that the Wii is selling substantially more than the Ps4 is after month 3. Couple this with the extreme growth in sales the Wii has for its second year, and it's obvious the Ps4 won't match it.

 For Europe, it's similar, but the difference is much smaller. First the data for total sold at the same points in time

And then the per month data.

 The Ps4 actually sold more in month 10 and 11 than the Wii did. This is largely a significant bump due to big releases, and they'd need to be significantly higher than those again to match the Wii's 15-18 and 18-21.

If we add them together, we get the following 2. Combined

And monthly

 Obviously, it's worth mentioning that we're here comparing slightly different time periods (both machines had slightly staggered launches), so I'll point out that the Wii launched 8th December in Europe, while the Ps4 launched 29th of November (the NA launches are 15th and 19th November, so they're the same for all intents and purposes).

The point with all tese tables is to illustrate that the Ps4 is already trailing behind the Wii in monthly sales, and the Wii had an incredible increase in sales in its second year. There is simply no way that Ps4 can manage anything even near it. The Wii will definitely overtake the Ps4 in Europe + America, launches aligned.

Thanks for the work you put into this.

Yeah, in the US the Wii is gonna race ahead no doubt. I guess it should have been expected since the console market is more fragmented between PS4 and X1 at the moment.

I agree that in Europe + US Wii will be ahead. I guess PS4 is doing exceptionally well in ROW, we know that it's tripling PS2 sales in Asia so I see your point about ROW being an expanding market. The Wii sould incredibly well in established markets for the first 4 years, it probably won't ever be matched.

Now I'm going to bed :p