If Mayor Newsom has his way 2800 "soft story" buildings in San Francisco would be required to do earthquake retrofits. Per this article a pre-1979 wooden structure with a home over a garage or store would be required to retrofit. The way I read this is that Single Family homes and 2-unit buildings with garages would be required to retrofit.
This appears to just be a germ of an idea, not a policy yet, but unless I'm reading this wrong, that effects the vast majority of residential properties in San Francisco. Only homes without garages, and obviously those already retrofitted, would not be effected.