From the New Geography blog on the "Let's-move-back-to-the-city!" hype now currently in vogue: "Most [large] cities are either far too expensive or too lousy to even be a option for most middle class families (still the number 1 buyer of houses)."
The author here is talking about the meme being put out by some that posits that because some trustafarians and childless yuppsters are moving back to the urban core cities and are loving it that there must be a major demographic trend at work. But then again with their means they'd love living just about anywhere, no? So in that sense it really is "all about the Benjamins".
Some aspects of this this phenomenon seem to apply to my hometown of Ann Arbor. A lot of folks who don't actually need to live in the People's Republic of Ann Arbor live or relocate to Ypsilanti or Pittsfield Township for the lower cost of living there or to Dexter or Scio Township if they have higher incomes. On the other hand there are also the old-timer hold outs (like me) and the folks that just like PRAA enough that they'll put up with the high taxes and the closed-off political system or in fact actively benefit from it. (And you guys know who you are.)
Gentrification on a very small scale doesn't prove anything. You can't build a large sized and thriving urban core with such a small albeit prosperous base.