edit: I couldn't figure out why I was a little confused reading this, but it's because there is no one coherent answer in this article.

edit: I asked because the article doesn't answer that, aside from a small sampling. And the phase before this seems to be from only a couple of years ago ("Aaron Leitko wrote a 2011 Pitchfork feature about it called 'Positive Destruction'.") I don't know SF, but I've seen gentrification up close a few times in larger US cities, it usually takes longer. Hence my question.