It's a bit early to predict since we don't know the price for each Sony/MS console and the definitive launch software line-up. Due to the pandemic and two models of each manufacturer I'd expect a bigger opening than Switch.

Bigger in terms of money spent? Sure.

Bigger in terms of actual units pushed? That's tough.

NS had a great first week, but suddenly dropped due to supply constraints, PS5 and XSX could beat its first two months if they'll have larger initial supplies. Beating its first week will be much harder.

Between the supply constraints and a non-holiday launch, I say switch is 2nd. I don't believe in the Xbox Series X having a fantastic launch, and certainly not beating 3.2 million. Plus PS5 has Spiderman and a holiday launch, in addition to faithfulness from the PS5 community I highly doubt it will sell less than 3.2 million was it?

You think is tough for Sony shipping less than 4 million PS5 this year?

Considering its going to be out for like 8 weeks I don't know about supply constraints. PS4 sold 4.2 million from launch to end of year. 

They're making less PS5's for launch last I heard and its going to definitely cost more. So we'll see. 

Because the Wii U was discontinued in January 2017.  Nintendo wasn't going to go 10 months without a home console in the retail space.  Nintendo was getting such bad press at the time, "Nintendo should go 3rd Party", that they had to launch a new console ASAP.  And that's what they did.

Latest rumor have that Sony upped orders from 5M to 10M for holidays (could be until March 2021 though).

If they really thought that Switch would do so much better if they waited for holiday them they wouldn't discontinue WiiU in January. They launching in March paid off.

Here's the Wii U weekly sales from it's last holiday period (2016) into it's worldwide discontinuation on January 31st 2017.  Tell me that Nintendo should have rode this out for 10 more months:

Week Ending 11/26/2016 (Black Friday)

Week Ending 12/3/2016

Week Ending 12/10/2016

Week Ending 12/17/2016

Week Ending 12/24/2016 (week before Christmas)

Week Ending 12/31/2016

Week Ending 1/7/2017

Week Ending 1/14/2017

Week Ending 1/21/2017

Week Ending 1/28/2017

When investors would have been questioning, what are you going to do about your home console selling 4,000 units per week?  I don't think "We're waiting for Christmas 10 months from now" would be considered a valid answer.

Sure thing, they were already questioning the previous 48 months.... and they could have released in 2016 as well but weren't able. Still that matches what I said prior that they try to release as early as possible instead of waiting for Xmas. If you can plan to have your swap on Holidays for safety on demand sure bonus points, but we have seem both PS4 and Switch sold out for 2 months on launch inside and outside holidays. So it more show that launch depends much more on inventory availability than Holidays.