Just taking SF for instance, my understanding is that the gayborhoods here have already evolved, twice. The first was the Tenderloin, then it drifted to the Polk Gulch. The fact that there is a concentration of old rundown, sad tranny bars and a couple of neighborhood spots in this area still in existence reminds visitors of this. THEN it went to the Castro. Also, straights are moving into the Castro, but I don't think many gays are moving out. The tech industry itself is very very gay, and that's the industry that pays and is sweeping the city. So as Castro becomes more expensive, lots of gays can still afford it. The # of bars/clubs has only increased and gotten better just since I've been here (Hi Tops for instance, Midnight Sun redo, etc), so that's not really a sign that the gays are leaving.
Besides, every other "group" that has formed identity neighborhoods in the past has seen these hoods "gentrified" (or turned into slums) at some point in the past. Gays often choose pretty awesome neighborhoods to be in, so it's no surprise that for the gayborhoods that been established for decades now that finally the ball is rolling and they, too, are becoming "gentrified".
The author also fails to point out that gays themselves were often the first "round" of gentrification. Many gayborhoods are former slums or rundown areas, until the gays came in the first place and made them "desirable".
The other thing is the fact that the author tracked same-sex couples. In our day of acceptance, many long term couples are adopting or having surrogate or basically just doing normal couple things, like "settling down". While some straight couples may see desirability in moving to a gayborhood with tons of bars and clubs, gay couples probably know better!
Once you want to settle down or have kids, then yea, a quiet family neighborhood (like Noe Valley here where so many gay COUPLES live) makes sense!! The Castro and other gayborhoods like it are better for gay SINGLES. Are they being measured or tracked?