Yesterday there were more than 25,000 people watching the live and they have more than 18,000,000 copies sold and the game is a single-player story mode with a year and a half old. I wouldn't say too high that Phantom Liberty is the only expansion, it may be a bestseller that pushes the decision to further expand the life of Night City with a second expansion in 2024 that would put the finishing touch to this stage of CDPR.
I don't know if this tweet has been posted yet in this thread but here it is confirmed