I agree with what you're saying except "a) Outlaw handguns and perps will carry shotguns". I think the perps will continue carrying/using handguns. They will get them in other cities or on the black mkt. in San Fran. Shotguns are too hard to conceal.
San Francisco will become a Mecca for criminals who will bring handguns with them from all parts of the country. Watch the murder rate go WAY up as law abiding citizens are left helpless aqainst gun wielding criminals. And those who dare to keep their guns and use them successfully for protection will be prosecuted for murder and perhaps even executed - after all, they must be made examples of because good liberals must never use guns.