August 2017 PS4 was at 19.9 Million. Thats December 2020 for Switch.
2019 October to December Switch sold almost 4 million units. So like 25.9 Million switch -vs- 19.9 Million PS4 is pretty possible in 3 month. That would be a lead of 6 million. PS4 was at 25.9 Million at the end of October 2018, that will be like 14 month later than Switch.
That really is impressive. Seems like Switch can surpass PS4 in the US while PS4 is still "kind of alive". (holiday 2021)
And maybe Switch will sell even more - even 4.5-5 million during these 3 month is possible.
I just remebered Wii and NDS December 2009 NPD Numbers. xD But I guess these numbers (for those who dont know: Wii was at 3.8 million units, while NDS was at 3.3 million units - and both sold roughly 5 Million units each during November + December 2009) will never never ever happen again.