San Franciso is a city, so I imagine what will happen is that companies will move out of the city limits and this new tax will be completely ineffective.
Seriously, how hard is it to find a new office in Oakland or San Jose?
When Connecticut hiked its taxes, even long-standing businesses headquartered there, like GE, packed up and moved to Massachusetts. (You know you're doing something wrong when "Taxachusetts" is a relative tax haven compared to your state.)
So even if these changes were implemented statewide, it can be an impetus to leave. Laffer's curve is a bitch for the eat-the-rich crowd.
Seriously, how hard is it to find a new office in Oakland or San Jose?