Anecdotally, what we found in Austin was a combination of two factors:

First, awareness of the futility and selfishness of "growth elsewhere" as a solution is much higher in younger people — and by younger, I mean currently under fifty. Generational turnover in Austin had been eating away at the NIMBY majority, and conversations about housing in Austin have long been polarized more by age than by left/right political sentiment. There's a caricature, with a strong vein of truth, of the old Austin leftist who has Mao's little red book on their shelves and thinks apartment buildings are an abomination, and Austinites of that generation are experiencing mortality. At the same time, younger people are adopting more and more urbanist mindsets compared to their parents.

However, I think a much much bigger factor was the influx of younger people, especially young people with experience of larger cities, diluting the votes of the older NIMBYs. Austin has been shaped by growth for half a century, but its "discovery" in the 2000s and very brief status as a darling of coastal hipsters (remember that term?) has had a lasting effect on Austin's popularity and its demographics. It's been twenty years since it was the "it" place for Brooklynites to visit, but in that twenty years, it's had a lot of exposure for young urban dwellers, and some of them discovered they liked it and moved here, bringing their comfort with dense living and their appreciation that growth can bring a lot of positives.

Personally, every homeowner I know in Austin has seen their houses depreciate significantly this decade, and I don't think it changed a single person's mind about Austin's housing policy. People who opposed the reforms are bitter about the outcome, and people who supported the reforms say it sucks for us personally, but it's what we set out to accomplish, and we're glad that it worked.