That's likely but very hard to say exactly tbh. With 360 and original Xbox we have the WW numbers. With Xbox One we don't, and I don't really what to compare shipped with sold through as that skews things. Hence why I'm saying "much more than half" to indicate that once again the ratio is skewed where USA is by far the biggest market for Xbox and is more than all other markets combined.
In regards to PS2. Here is a graph of PS2 Vs PS4 shipments. Please note that the following post looks at worldwide shipments unless otherwise explicitly stated.
Now lets take a look at why the PS4 is ahead.
PlayStation 2 launched in Japan first on March 4th 2000, on its first day alone more than 600,000 were sold at retail and 380,000 through online pre orders. The PlayStation 2 had issues with chip production in 2000 and demand for PS2 was high but Sony were unable to fully cater, even on day 1 they could only actually ship 720,000 of those 980,000 orders.
In Japan sales were high over 2000 and everything that was being shipped was being sold. And here is the key, the first 7 months of shipments just went to one country, Japan. Those first 7 months on the graph account for 3.5 million units that were shipped in Japan only.
The production issues hit the western launch as well with Sony able to only ship 500,000 units to the USA in October, half what they actually wanted to ship to meet demand. Overall Sony were just able to ship 6.40m units in 2000 which was a lot less then where they wanted to be. In fact If I remember correctly they planned to ship at least 1m more worldwide but were unable to. As of the end of 2000, which is month 10 on the graph, the PlayStation 2 had shipped 3.94m units in Japan/Asia and 2.46m units in North America and European countries.
In 2001 (Month 11 through Month 22), Sony were able to solve production issues and get back to selling as they planned with a total of 18.6 million units shipped worldwide taking the cumulative total to 25 million as of the end of 2001 (month 22).
Now lets look at PS4. Unlike the PlayStation 2, Sony's fourth console launched in North America and Europe first, in fact the PlayStation 4 launched in a total of 53 countries and regions during its first two months and expanded to 123 countries by month 15.
So this is a major factor why the PlayStation 4 outsold the PlayStation 2 for the first 7 months easily, because the PS2 was only available in Japan where as the PS4 was in more than 53 countries during the first 2 months and by the 7th month had launched in 72 countries and regions. So whilst Japan is big for gaming, a console launching in 72 regions in 7 months (inc NA+EU) is going to see more sales than a console that launched in 1 country for 7 months.
The PlayStation 4 saw over 1 million shipments in North America and over 700,000 in Europe during the first 24 hours on sale in those territories. Easily surpassing the PS2 launch and solidifying the PS4's early lead in the generation 8 set of consoles. After just two months the PS4 had sold in 4.5 million units in these 53 countries compared to the PS2 which had just sold under 2 million in Japan at the same time aligned.
The PlayStation 4 sales were high because, as mentioned above, the console launched in more territories, it was at a compelling price point and because it was coming off a very long generation where gamers were ready for a next generation console, even the Xbox One had a massive launch because of this final reason.
In 2014 (month 3 through 14), the PlayStation 4 saw continued demand and sold in an additional 15.4 million units. This is slightly less compared to PlayStation 2's 18.6 million units in 2001 (month 11 through 22). The reason for this is because it was still early days for the PS4, Japan did not contribute as much (only 1.1m in 2014 vs 4.3m in 2001) and because the PS4 had competition from the Xbox One where as the PlayStation 2 only had competition in the latter half of 2001.
The PlayStation 4 as of month 14 had sold 19.9m units worldwide where as the PlayStation 2 had only sold ~12m worldwide. Again the 7 months of just Japan only sales really comes in to play here.
The PlayStation 4 is currently at 22.3m units worldwide after 17 months where as the PlayStation 2 was at ~16.5m at this current time when you align launches.
This is a stupid thing to do but If for example you just look at worldwide sales outside of Asia (so 17 months of PS2 and PS4 sales outside of Asia), The PlayStation 4 would be less than 21m and the PlayStation 2 would be over 19m. So very close, and this again shows the impact of those 7 months of Japan exclusive sales and why PS4 is, when aligned, comfortably ahead of the PS2.
However the PS2 goes on to sell gang-busters in 2002 and 2003 and was the fastest console of its time to reach 50 million. Right now I expect the PS4 to fail to break that record and reach 50m just after the PS2. Main reason being competition from Xbox and lack of sales in Japan to boost overall numbers, sure the numbers will come from emerging territories but 20m+ sales in Japan alone for PS2 really helped PS2 get to where it is today.
Sorry for any mistakes in this post.