> the tech firms are unlikely to leave, meanwhile SF can get more taxes from them (many of them were historically given tax breaks, like Twitter, to move into the mid-market area).

Twitter's highest paid executive looks like they make something in the $7M range (Dorsey's total comp is approximately zero for several years, as he is counting entirely on capital returns on his investment, not compensation from the firm); I'm doubting that their median SF pay is below ~$70K.