2021 should be in the bag, but it's unlikely to continue for another 1-2 years following that. That would require either an unprecedented sustained sales curve for the Switch or a historical low for PS consoles. Both seem unlikely at this time. We'll know more about PS sales some time into 2021; launch windows are a really poor metric for extrapolating future sales. 25 million is a big ask for the Switch for 2021, let's remember the unnatural circumstances for the market in 2020, with the highest ever selling Q2 of any year, starring two consoles in the twilight of their lives. 2021 will likely see a more normal sales trajectory for all parties involved.
25Million isn't a big ask for the Switch, we have never seen a console in history have sales drop more than 6 million units the next year unless a successor is right around the corner. If anything the Switch is more likely to sell above 25M in 2021 and I believe that even without this pandemic that the Switch had the opportunity to sell 25M in 2020 with Animal Crossing leading the way and globally speaking the Switch was already up YoY in 2020 before the pandemic started. Plus you have to keep in mind that this virus doesn't look like it's going to end anytime soon heading into 2021. Also, I think there's a chance we see a stronger 2021 year for Nintendo since it's probable that many games planned for 2020 got pushed into 2021 which will help Switch sales. Also the possibility of a Switch Pro and more.
Also, it isn't unlikely that the Switch continues to outsell the PS5 in 2022 and 2023, PS consoles have a difficult time hitting 20M years most of the time and I still think the Switch could sell in the upper 10M to lower 20m in 2022 and possibly 2023, which would be enough to still outsell the PS5 in those years.