You also cannot ignore the other factor involved with covid, and that is that many people will need to be wiser with their spending.  With that said, services like gamepass are a godsend.  Not to mention the day 1 exclusives that will grow the value of the service even more with time.  MS may have fumbled last gen with 1st party titles, but they now have more studios under them than ever before.  One does not spend 6.5 billion USD for a massive acquisition like Bethesda if you are not in for the long haul.  As I have said before, the Series consoles will not outsell the PS5 worldwide.  They will however have a much higher stake this generation based on their pro consumer moves of late, which will impact the bottom line of the PS5.

As for Switch, you are lying to yourself if you think devs that already support it will drop a massive and growing user base like that.  Next year will likely be loaded with 1st party exclusives and could even see BotW2.  Capcom is releasing a console exclusive title in Moster Hunter Rise and most Japanese devs are shifting their focus to Switch over Playstation as Nintendo dominates that region.  So to sum it up, Nintendo is not going to get any worse 3rd party support than they already have.

And mark my words on this, if the Switch sells less in 2021 than it did in 2020, it is not because of decline due to new Sony and MS consoles.  It will be soley due to the Switch just selling such a monsterous number in 2020 itself.  Another thing you are forgetting is that unlike the XSX and PS5, the Switch can complement either of those two better than they can eachother.  Most multiconsole gamers will either own a Switch/PS5 or Switch/XSX or S.

So yeah, saying the Switch will pass the PS4 os actually a pretty realistic bet.  I wouldn't call it a safe bet, but certainly not a longshot by any stretch of the definition.

It all depends on new market growth and how much Microsoft can claw back existing users from last gen on where the PS5 will end up.

Translation to early to tell.

Microsoft leaving consoles behind? Wishful thinking?

This question is basically a variant of "will PS5 do better than Xbox?". The sales of PS5 and Xbox together will be greater than Switch, so it all depends on how much of that market Sony gets...

Well, first I take issue with sales dynamic of Nintendo consoles, as many of them had very different sales dynamic.

But onto the question in the thread title. Obviously it is very early to guesstimate lifetime sales, but I think we can make a few guesses here.

I think nobody disagrees, that Switch is on track to outsell PS4. So comparing PS5 to PS4 might be the easier task. Sony consistently is loosing foothold in Japan. That was visible with the PS3 and PS4, and I have no indication that the trend is reversing. Sony has a strong base in europe though, and I think it can grow in the rest of the world, as Sony is pushing into new markets. America is always a place of fierce competition though. And I see not much room to grow in europe or even Sony losing a little ground.

The reason is that this gen the competition will be more difficult. Xbox fumbled last generation, the series X/S look like a much more promising combo. But there is also more competition outside the console space. First of all is PC becoming a lot more viable with newer and easier tech and Gamepass as a very value heavy offer. I see some players moving to PC. But there are also multiple streaming services now popping up, changing the face of gaming. They may very well take a big load of console customers and offer them access.

Now, classic hardcore console gamers may scoff at these ideas, but no one sell 100M+ consoles to classic hardcore console gamers. Many gamers enjoying multiplatform games may very well move to PC or streaming.

So in conclusion: I see PS5 barely reaching PS4 number. As we established Switch probably will outsell PS4, this means PS5 will also lose to Switch.

Again, this is pretty early, some major things may change. I just don't see them so far.

We're back to the cliff theory, I see.

I think the PS5 will end up right around PS4 due to it having a lot more competition. But I don't think it has any chance at Switch. PS4 ~125 million, PS5 115-130 million, Switch 140-145 million.

if you mean lifetime sales, it entirely depends on the Switch Lifespan, assuming Nintendo will keep following with the Traditional 5-6 Years Lifespan, on which the Switch successor would release around 2022-23 and the current switch sales would drop after the announcement (similar to how DS sales dropped of cliff following the 3DS announcement in 2010-2011, similar to Wii after Wii U announcement)

as for weekly Sales id Say the PS5 will outsell the Switch around 2022 (again Depends on how longer The Switch Lifespan is)

High chance of this being a heavily quoted post in let's say three years or so from now.

The Switch will be Big for sure, but i Doubt it would reach the Juggernaut DS level (let alone PS2), 2019 was a massive year for the Switch in terms of Games (Pokemon Sw/Sh, Smash Ultimate, FE, Luigi Mansion 3, Astral Chain, Mario Maker 2, Ring Fit and Links Awakenings Remake), as well as a new cheaper model and yet it barely sold more than half of Projected 2020 Switch Sales (with only hyrule warriors and AC), Covid-19, lack of competition from sony, microsoft (due to Next-Gen being around the corner) definitely boosted the Sales this year, the real test imo is whether the Switch will keep the Momentum Next year sales-wise.

my estimation would be 140-145M lifetime sales.