Parks Department filing talks of educational programs (a "social justice-themed" tour for woke schoolkids), a "restaurant or café," and a "retail operation." It would presumably show art, too, though it's hard to say how ambitiously. Mainly the building might be used for art storage. The 84,000-sq.-ft. structure is a quarter the size of Zumthor-LACMA (which is no larger than the buildings it would replace).
Why South L.A.? Michael Govan told Charlotte Burns, of the "in other words" podcast,
"Because LA is a spread out city, it’s just not true that people travel to every neighborhood, and that everyone can get to Lacma. The idea of a de-centered museum in a de-centered metropolis is emerging as a strong idea. You could literally run a space in South Los Angeles, and then run a space in San Fernando Valley. There would be no overlap in audiences between Wilshire Boulevard, San Fernando Valley and South Los Angeles. None.… "
Museum satellite facilities is an idea that's gone in and out of fashion. Early versions skewed upscale, corporate, and suburban. More recently museums, like Millennials, have gravitated back to close-in and gritty urban neighborhoods. This has happened against a grassroots pushback against gentrification.
55th and Avalon is no Boyle Heights, not yet. Would a LACMA satellite bring in the galleries and coffee shops and hipsters? I wouldn't bet against it. A generation ago it was a progressive talking point that museums should be in the inner city, not on a wealthy hilltop. Now that such possibilities are on the drawing table, the mood is more ambivalent. One might think that an art museum would be a more desired neighbor than a water treatment site. But L.A.'s crazy rents may be changing even that.