Zoning is primary, but without rent control, the Tenderloin would be a lot better (convert the SROs into reasonable rentals). Of course, getting rid of the enablers of homelessness would also be necessary.
It's not rent control that keeps SROs around - there are separate SRO controls. You're not allowed to eliminate SRO beds without building replacement beds in another part of the city (or paying into a fund to cover the cost of someone else doing it, and it's a significant fee.)
Many of the people in SROs have substance abuse or mental health problems or other disabilities, and most (?) SRO tenants are paying their rent in federal housing assistance vouchers (which is why SROs can be so profitable - the government pays you a high price to house people that otherwise wouldn't be welcomed on the rental market, housing discrimination laws notwithstanding.)
Any zoning plan has to make space for this population somewhere in the city. If you let people demolish SRO beds, you're just going to discover that you have to build new ones at public expense.
