The San Francisco Board of Supervisors will vote next week on a temporary moratorium on new market-rate housing in the Mission District. Supervisor David Campos proposed the 45-day halt on permits for new housing developments as a way to reduce the displacement of long-term residents in the neighborhood. Projects composed of below-market-rate units would be allowed. But critics, like Supervisor Scott Wiener, say the plan will actually make housing more expensive and lead to further displacement.