Sony has said they target a bigger number of PS5 sold in the first quarter than the PS4 so I went with 16-17.9m.

Bonus: Final Fantasy XVI then God of War: Ragnarok

So far, if I recall correctly, it's been doing worse than PS4, particularly in Japan. It's hit an all-out slump in Japan, and Japanese sales have always been very important with Playstations.

I'm going with less than PS4. 10 to 12.

Japan is much worse yes but it's been outpacing the PS4 in NA and Europe. Worldwide, it's ahead on PS4.

Stolen from @dmillos in the HW thread : 

Is this gap weekly or cumulative? Seems weekly as I think it is unlikely the cumulative gap drops that much.

20 - 22 Million

It is cumulative. Might as well include dmillos' other graph:

The next few weeks are going to be interesting as we see how PS5 behaves outside the holiday boost.

I'm saying 16-17.9M. I think the people who chose 20M or over are very wishful thinkers. I don't think there has ever been a console that sells over 20M in their first year. In fact, selling 20M in a single year isn't necessarily the most common thing for consoles anyway. I think the Wii, DS, PS2, Switch and PS1 are the only consoles that managed that. I'm not sure about the Gameboy, but I'd imagine that one did too. Still...that's six consoles out of the history of the videogame industry.

Expecting the PS5 to hit that mark in it's first year when sales are often lower than their peaks is just not likely, IMO.

Wait, PS5 is launch-aligned in total only 280K ahead of PS4 anymore? OK, then the sales were very much frontloaded. Seeing the second graph shows this. After the first two weeks (second week is european lanch if I remember right) there is a sharp drop and not much of a christmas boost. Hmm. It really is interesting to see how PS5 goes on in the new year. I thought outside of japan the PS5 was strongly ahead of PS4, but it looks much closer in reality.

This graph does not look good for PS5. They had a fantastic launch but haven't looked impressive at all since those two launch weeks. Selling significantly worse than PS4 after the launch weeks. I'm sure PS5 will be fine overall though, but I have no expectation of it being some record breaking seller that some people are expecting. For 2021 I'd expect 14 or 15 million sales for the year, on par with what PS4 did.

I think it will be anywhere from 16 - 18 Million. The PS5 demand is unprecedented if we're gauging social media metrics, likes, etc. Add to that massive system sellers like HFW, GoW & maybe even GT7.