The US is very close between all 3.

Without the stock issues it probably would've fallen behind permanently at a similar point but thanks to that it'll happen at least an entire year earlier, ouch.

Never say never; the shortages of the early 9th gen may lead to a longer than usual generation as Sony and MS try to make sure they get their money's worth out of their current consoles. PS5 could pull a Switch and go into overdrive in year 4 or something, once supply is no longer strangling it.

I concur it seems unlikely at this point that PS5 will catch up to the Switch, but I'm sure in 2015 most folks would have said the successor to the Wii U would have absolutely no chance of outselling the PS4, yet look where we stand now.

The gaming market is extremely hard to accurately predict beyond the short term.

best buy seems to have in stock every time i look

Depends on where you are.

Australia has plenty of stock, Amazon US has it in stock since early February and Best Buy has it in stock atm, some people report there are no supply issues in Japan.

Don't know about Europe or the other markets.

We're not in 2018 though which for the PS5 and Xbox Series would be the equivalent of 2015 for the Switch. By April 2015 it was very clear that the PS4 would do a lot better than the PS3 and the Xbox One a lot worse than the 360 since the sales potential of Playstation and Xbox consoles get decently locked in quick. Stock issues do muddy the waters some but the PS5 getting a notable surge when the supply issue is fixed would at best make it fall behind permanently about the same time the PS4 did. I'm confident in saying that the PS5's best years will be a lot lower than the Switch's since its 2020 and 2021 sales are massive.

Even in early 2020 nobody foresaw the Switch skyrocketing the way it did. The pent up demand for the PS5 is enormous, once its available in sufficient supply I see no reason it can't hit similar highs as the Switch.

The reason I can't see that happening is pretty strong competition from Xbox this time. I could perhaps see its peak year potentially falling into the 20-22m range due to pent up demand but would be quite surprised if it had a year in the 25-28m range. The latter would indicate it selling better than the PS4 which I see as very unlikely at this point.

Xbox is doing better than last gen, but right now their performance is inflated by having SKU they can actually make enough stock of, the Series S, which is the only 9th gen console widely available. Once supply improves PS5 will be beating Xbox easily.

Switch market is arguably bigger, as it compromises both stationary console gamers and handheld gamers, no Sony home console will ever have as much short-therm demand as Switch had. Well, "ever" is a strong word, it can happy but it will need an increase in hardware market from things like:

- Same people spending more on games (and buying hardware) (*)

- New people spending more on console hardware 

- Gaming becoming less expensive, allowing people to buy more hardware 

Without any of this, the only way PS5 can sell more is to have an extended life with several versions/revisions, like Switch is getting. 

Besides, if Switch (which is a handheld in terms of manufacturing) from 2020 to first half of 2021 suffered stock issues, I doubt Sony can ever produce as much PS5 as Nintendo couldt with Switch in a sustainable way regardless of the demand 

* off topic, I think Switch exploded after people opening their wallets to buy another console wich happened because PS4 and Xbone were old enough to yield a purchase of another console, which probably wouldn't have happened if Switch was a dying platform. In this sense, launching so long after PS4/Xbone was a strategic win. Worth nothing this explosion happened right after people were in lockdown and rediscovered gaming is fun