End of 2022 seems to be the most likely. Even if Switch Pro releases in 2022 instead of 2021, I'm sure it will be before the holiday season that year. I also imagine we will see a price cut of at least $50 for both the regular Switch and Switch Lite long before the end of 2022 (I'm guessing it will be by Holiday 2021). I could see the Switch being around 122 or 123 million units sold by the end of 2022, so that should be higher than PS4's lifetime sales even by then.