@XtremeBG I was fortunately able to make calendar year graphs for the Switch & DS since Nintendo has complete quarterly shipment data going back to 2004. Before that it was limited to six-month periods or entire fiscal years. Sony has complete quarterly data for the PS2 out through the end of 2011, but they started to combine PS2 & PS3 shipment data for a couple of years. Unless that split is buried somewhere in their reports, there doesn't appear to be any data available to make a complete set of calendar year shipments. Another thing about the PS2 was the offset launches. It was released in Japan seven months before it was released in North America, hence those weak shipment numbers in its first FY.
Anyway, the PS2 benefited from strong post-replacement legs, selling far more after it was replaced than any other system before or since. Meanwhile, though the Switch has had considerably weaker legs, it has benefited from an abnormally long primary life cycle (8-¼ years vs. only about 6 years for the PS2; only the Game Boy lasted longer before being replaced). So, both advantages result in a relative wash. Kinda like how the DS had better yearly average sales than the Switch during its primary life cycle, but said life cycle was cut short with the release of the 3DS. If Nintendo had waited another year then perhaps the DS could have cleared 160M. There's all sorts of factors that influence the sales of a system... which sadly some people treat as more than just matters of academic curiosity, but that's a topic for another discussion.
Speaking of factors influencing sales, the regional dynamics between the PS2 & Switch are also interesting. While we never got a final official regional split for the PS2, we can make reasonable guesses.
The final tally in Japan was about 22M. That was the last time a home console sold well in Japan, with the Wii selling only 12.7M and subsequent PlayStation systems not even selling half what the PS2 did. Meanwhile, handheld and semi-handheld systems have continued to do well in Japan. The PSP sold almost as well as the PS2 did there, and where even the 3DS did well enough to become the new #4 console of all time.
While the U.S. is the majority of sales for its region, the splits are kinda all over the place for systems where we do know the final split. For Nintendo systems that's typically been around 85-90%, but interestingly enough the U.S. was only about 75% of the share for the PS1. That gives us a wide range, one that puts lifetime sales in NA somewhere in the neighborhood of 52-55M assuming a Nintendo-like split and as high as 62M assuming a PS1-like split (VGC has it at 53.65M). However, it's entirely possible that said split was skewed because of how the N64 was far more popular in the U.S. compared to other countries in the region, relative to the size of the market, which may have depressed the U.S.'s share of sales for the whole region. It's entirely possible that with the PS2 being much bigger in the U.S. than the PS1 in both absolute terms (54% gen-over-gen improvement) and market share, its share of sales for the region may have improved and that 52-55M range is more probable, and that 75% share was anomalously small.
That leaves as much as 83-86M for Europe, the rest of Asia, and other smaller markets, though possibly as low as 76M. The last update we had for PS2 shipments in Europe had it at 48M as of May 2008, and since it was on the market for another several years after that it had to have shipped at least 50M in Europe (VGC has it at 55.3M). So, that leaves at most around 33-36M for smaller markets.
The Switch has far surpassed the PS2 in Japan, having sold over 36.5M units and counting, a lead of over 14.5M units. In the U.S. it is just barely ahead of the PS2 as of the end of 2025 (~48.5M, vs. 46.5M for the PS2), and it's reasonable to assume a similarly slim lead for NA as a whole. Meanwhile, in Europe & ROW it's way behind the PS2. As of Dec. 31, Nintendo has shipped 39.91M units to Europe and 17.87M to other markets outside the main three. That's a total of almost 57.8M units, far less than the well over 80M units the PS2 had to have sold outside NA & Japan.
Or if you want to simply things, U.S.+Japan sales were 68.5M for the PS2, leaving 91.5M for all other countries. Meanwhile, U.S.+Japan sales for the the Switch was at ~85M as of the end of 2025. Leaving, say, 1M of shipped units left unsold worldwide at the end of 2025, that would leave ~69.4M for LTD sales in all other countries, a difference of about 22M in the PS2's favor, enough to offset the combined lead of 16.5M for the U.S.+Japan. And thus the roughly 6M deficit it currently has.
While the Switch was a hit everywhere, the scale of its success varied from region to region. This is why worldwide sales don't ever tell us the whole story by themselves. Every region has its own idiosyncrasies, with customers having different buying habits. Handhelds do better in Japan relative to the size of the market. Europe is "PlayStation Country" for the most part (and in fact was a small market for consoles prior to the PS1). The U.S. & Canada are more flexible and seem to exhibit less brand loyalty overall. As a result, every system has different splits across the various major markets.
Of course, the Switch is still selling and probably won't be discontinued for at least a little while longer (maybe the end of FY2027-28), so its U.S.+JP lead will grow and its combined deficit in other countries will shrink. But as I pointed out in the "Road to 160M+" thread, the Switch is trailing the DS considerably in terms of post-replacement shipments/sales globally, with the situation being kept from being worse only because of Japan, and even there it is quickly losing steam. If it continues at that rate, it won't come close to the nearly 6M more it needs to reach 160M. So to answer the OP's question, my answer is "It won't." It should clear 157M, but ~158M is about as high as I'd go.