Xbox one was a failure on all counts. The marketing was awful, the brand was in shambles. Series has been already more solid and will benefit from the acquisitions later on in the generation. X360 had a stellar performance in the US and i don't think microsoft grew globally to reach thoses numbers again. So i think it's fair to say it might end up at around 70-75 millions imo.
But idk, microsoft seems a lot more aggressive this generation and my pull a lot of cards to boost their install base. Afterall, it's not the profit on the console that they are after but gamepass. So they might sell it at a really low price in the coming years.