Imma say 60-65 Million, Xbox now has the price advantage this time around so I think that'll convince more people to buy an Xbox over a PS5, plus Xbox Game Pass might be attractive to people.

Now this is a system where I'm not at all sure that they're gonna stick to the regular 7 year lifecycle. It seems to me the Series brand is made to make room for revisions and additions over the years. Xbox Series XL, Xbox Series X^X, Xbox Series BOX, the possibilities for great names are endless. I'm not really gonna guess a lifetime number, but I do think the Series will continue to outperform the sales rate of the Xbone while never reaching peak 360 numbers.

Early to say, but I'll predict 60 million.

Xbox does fine enough in North America and Europe, but is a nonfactor in Japan. Xbox is also the least-focused on the hardware. They want you to play Xbox, but they could mean on Windows or other means. They're more into gaming services. Some people hype up the first-party studios they've acquired, but I don't think it will make a big enough difference for the Xbox Series to get close to the lifetime units of the Xbox 360.

Around 65 million 

70-80m

This is assuming the First party delivers some bangers

40~45 million will be sold by the end of 2027.

Yeah, 70-75 million. That's a 50%ish boost on last generation.

So far it seems to be doing better than it's immediate predecessor, so I'll go with the 60 million neighborhood.

50-75 million seems a safe bet, but it's very hard to nail down whereabouts in that range it will fall.
It's sales are higher than Xbox One now, but we have yet to see if it can sustain this pace beyond the early adopters phase. I remain skeptical of it greatly exceeding its predecessor, but I'm reserving judgement until we if it performs post-year-one.

I think it will outsell the Xbox One, but I'm not sure about LT sales.

Maybe 60-80 million.