XBS: 60 mil
PS5: 100 mil
I think that the two consoles might be equally fast out of the gate this year. Judging by the production difficulties that Sony seems to be facing it looks as if their huge advantage of the higher PS4 install base will take longer to move over to PS5. I also think the Series S really is the man of the hour when it comes to the casual/family market and coronavirus, especially with All Access and Game Pass.
In the long run PS5 will take the lead and run up to 100 mil. It always will for as long as the traditional console market survives, because of its dominance in Europe and ROW. But I could easily see that with a strong start and with the growth both of game pass and of cross-platform play that XBS could repeat Xbox 360 successes in the anglosphere.