56-60m,
2018- 9m. I think it will remain up YoY enough before the same week X launched to stay up YoY overall along side a massive holiday season with X1X hitting $449 with a bundled game as a standard price point giving the X1 around 9m and been it's peak year which would take the total for end of 2018 to around the 45m mark.
2019 - 6m. YoY drop is expected but early 2019 is loaded with third party big hitters and Forza Horizon 4 been the go-to bundle through most of the year, I also think holiday will see the X1X at $399 with a game as standard price (possible lower through temporary deals and Black Friday) to make a big push on the X this year and the S been at $199 with a game bundled.
2020 - 3.5m. The year Next box and PS5 arrives and will likely see a a big falloff here on out, A cross gen Halo Infinite launch could help boost sales a little higher with a low priced S bundle.
2021 - 2m. I think sales will fall off quite sharp as next gen has hit and we know that the Next box will fully support all X1 games +360/OG BC titles leaving little need for the X1 except to families buying it due to the cheap price point it will have at this point.
2022/23 - <1m. I think it will have a shorter sales period than that of the 360 and be discontinued in 2022/23 after 9 or so years on sale. There is a little twist that could happen if they somehow use the X as an entry level into next gen as some rumours say but I can't say I'm really sold on that one.
Lifetime Xbox One sales 57m.
