San Francisco is ill-prepared for an 8.8-magnitude earthquake simply because there are too many old structures in the city. Underground structures that were built on top of will collapse. Anything not built to modern standards will fall over. Infrastructures will be devastated and gas explosions will rip the city apart.
I would doubt that San Francisco would be ready for an 8.8 magnitude earthquake. This would be a huge earthquake that would cause mass destruction. I am not very familiar with the city or it's earthquake precautions but I would guess that no city could completely compare for such a large earthquake.
Fortunately, we do not expect a magnitude-8.8 earthquakes to be widespread in the United States. Such large magnitude earthquakes require very long faults that are capable of rupturing all at once. Only two such faults appear to have the capability to generate very large earthquakes: the Cascadia subduction zone along the coast of Washington, Oregon, and Northern California and the Aleutian subduction zone along the southern coast of Alaska.Three problems remain, however. Well over 80 percent of California’s buildings and systems were built before these most recent changes. Half of these older buildings will be severely damaged and unusable; many will need to be replaced.
An 8.8 magnitude earthquake would be a truly disastrous occurrence. While I'm sure it's likely that San Francisco would be able to deal with this far better than some random city in the Midwest that has no experience with earthquakes at all, it would still be a catastrophe and it's likely many people would suffer greatly. I think, on that level, it's impossible to really "prepare" for something of this nature.
While San Francisco is perhaps one of the most prepared cities in the world when it comes to earthquakes, I feel like the city would still be in serious peril should an 8.8 earthquake strike in the Bay Area. An 8.8 earthquake would cause considerable structural damage to roads, bridges, buildings and the city's infrastructure, not to mention the possibilities of a tsunami.