It would be good if Bay Area goes the way of NYC, London, etc by densifying the urban cores of previously suburban towns. For example, I see that Mountain View, Sunnyvale and Santa Clara are rapidly densifying with many newly constructed apartment buildings, TH etc on El Camino and other main roads. SB 9&10 may allow that densification to start occurring in the SFH neighborhoods, which are still having the same character as they had in the 1980s. I think this is the more likely and good outcome.
But if the densification is allowed to run amuck, eg., by building 8-10 apartment units on each residential parcel of 6000 sq ft which currently has a SFH, then Bay Area may go the way of Bombay, Dhaka or Lagos