Suspect they'll have another PoE situation on their hands (First game sells reasonably well, second game fails due to lost interest)
I'm of two minds on this. On the one hand, I think you're correct and that nobody really wants a sequel -- I think a large part of the original's success as the novelty, exploring the new universe, etc. But it was not good enough to warrant continued interest.
On the other hand, now being firmly in the grip of Microsoft who is looking to expand their territory when it comes to original ("original") IP, they might pump a hefty marketing budget behind this. Plus, they can always throw it on Gamepass.
That said I doubt they will hit 10 million units sold. I think they hit 7.5 if they're lucky. 10 million is immaturely optimistic. Unless, of course, the game is phenomenal and departs significantly from the first one in terms of mechanics, etc. Which it probably won't.