I have to admit that, for example, when Tzipi lost from 4-1 in the 3rd in AO 2000 (to a Mexican player that retired soon afterwards), I thought she blew her chance to for a slam MD win. It took 4 years but eventually she had four.
Julia will get more MD wins soon enough and I don't see her going away either - she should establish herself in the top 100 and she's good enough to do that; however, she's not a future top 20 and better players than her never made the last 16 in a major.
I do not like to talk about her potential, as I have always been wrong. In the beginning of this year I felt that she would never make it past the top 130. If you asked me right before her run in the summer of 2012, I would have told you that she would never re-enter into the top 200. You never know with Julia. She could surprise you. I think she played like a top 50 player this week. Top 20, I don't think so, but again, she has always managed to spectacularly exceed my expectations. And yes, better players have never made the round of 16, but with the enormous amount of grit and fight that Julia has I find it hard to believe that she will never even be in this position again. She can give a lot of really good players some trouble on the tour. Hopefully she starts playing some WTA Internationals to get herself more established.