All that has to happen is tax revenue has to fall and the spending will decrease and the homeless will go to some other place where they can live a better drugs and camping lifestyle. Having lived for some time a few years ago in the Tenderloin, the idea that the homeless in S.F are normal people who have fallen on hard times is a complete simulated reality that has almost nothing to do with the actual situation.
SF is the solve everything with more money city because more money is always to the benefit of people working government jobs. For another example, look at the 1 billion dollar per mile recent subway extension, for example. That 1 billion went to somebody and employed a lot of people.