Whether the city's culture or the tech community's attachment to the region will break first is, of course, an open question.
1. SF could double it's current housing density tomorrow and still have less than half of manhatten's density. That's not a serious concern.
2. Even if it were, we're faced with a tough choice: preserve SF's low-density housing, or preserve it's people. Which is better: a city with 20% taller buildings, or a city where the only the rich can afford to live, secure in their $10m victorians and $5k/mo NEMA towers?
3. Many would argue that SF's uniqueness is its population, its freespirited attitude, and its rich history of art and culture. The buildings themselves are only a small part of that. Losing them would be a bummer, but far worse than losing the real soul of the city.
Count how many bridges and tubes connect Manhattan to the mainland vs. how many bridges and freeways connect SF to the rest of the world, and revisit that concept again.
So it doesn't have to be high rises and skyscrapers. SF can look like SF and build enough to make living affordable.
Of course, the real problem is the peninsula cities that insist on densities much lower than one third of SF. 80% of buildable land on the peninsula is tied up there being wasted.
Also, Hong Kong is a rather beautiful city.
It seems bizarre to me that those most fervently opposed to the influx of tech in SF are doing the most to harm the existing residents. If you make it hard to build in San Francisco, there won't be enough houses. If there aren't enough houses, who do you think gets the few that remain? It's not the freaks and the weirdos– it's the wealthy. The freaks and the weirdos have to leave because of your shortsighted policies.