San Francisco wants to turn Central SoMa from a humble caterpillar into a beautiful butterfly. On Thursday, the Planning Department finally unveiled its long-term (the next 25 years or so) plans for the neighborhood.

The city defines Central SoMa as the area south of Market street, north of Townsend, and squeezed between Second and Sixth. It’s a zone that includes SFMOMA and the Yerba Buena neighborhood, loads of low-income housing, and nearly 30 landmark buildings. Notice that it’s also the future home of a long swath of the incoming Central Subway.

The new 178-page update to the Central SoMa plan lays out the city’s goals for the neighborhood in the next quarter century: Add 7,500 new homes (2,500 of them affordable housing) and 50,000 new jobs to the area, generate $2 billion worth of public benefits, save the Old Mint and other historic buildings from disrepair, generate new parks and pedestrian byways, and do it all without displacing affordable housing, arts and artists, or anything important to SoMa’s history and culture.

And for our next trick, we’ll also juggle flaming knives while building a scale model of City Hall out of playing cards.

Okay, so the plan sounds ambitious. Basically, it’s do everything everybody could possibly want. But the pitch isn’t short on specific policies to make this stuff happen. Some are simply guidelines, like "Ensure the neighborhood’s industrial and arts legacy are not lost." Others are decidedly more granular.

Some highlights:

Rezone blocks that don’t presently allow for housing. (This really sounds like something that should have happened already.)

Raise height limits on SoMa parcels, some of which are presently as low as 30 feet.

But don’t block out important views, like those from Potrero Hill.

But do encourage developers to build tall enough block out the freeway, which presently "looms large" over everything and kills the mood.

Even so, "visually diminish upper facades" of tall buildings so that nobody feels loomed over by the new stuff either.

Set requirements that affordable housing contributions actually be built in the Central SoMa area even if not built on-site.

Allow affordable housing developers to sell off unused developments rights.

Also demand that at least half of larger plots be dedicated to non-residential uses, and add ground-floor retail requirements to streets like Folsom and Fourth.

While we’re at it, require new PDR space as part of large commercial developments to help make sure there’s no net loss of arts and creative space.

But don’t allow a net loss in housing stock from redevelopment, and particularly quash demolition plans that might combust low-income housing or rent controlled housing, and of course any of the neighborhood’s 29 landmark buildings.

Widen sidewalks, add additional crosswalks, and throw in trees and other sidewalk decoration wherever you can.

But also make sure that new buildings fill up their parcels all the way out to the sidewalk, since "when buildings are set back from the sidewalk, such as in a suburban strip mall, people on foot feel exposed and detached from their surroundings, leaving adjacent street traffic as the defining experience."

Build a giant new park, "possibly near Caltrain rail yards" to be the neighborhood’s centerpiece, the way Alamo Square, Bernal Heights Park, Washington Square, and Dolores Park do for those neighborhoods.

Finally, encourage "gritty architecture" that imitates the brick and masonry already fairly common nearby.

The new neighborhood plan will start working its way through the political process in November. If all goes as planned, the city will officially adopt the final version next May.