The Folk Art Museum building, designed by Tod Williams Billie Tsien Architects, will soon be no more. The Museum of Modern Art (MoMA), which acquired the building in 2011 and announced in January that the townhouse museum could not be preserved in MoMA's next expansion, plans to dismantle and store the museum's weathered façade panels. According to a report in The New York Times, the 63 copper-bronze alloy panels that served as the face of the Folk Art Museum for a decade will be removed and put in storage. “We have made no decision about what happens subsequently, other than the fact that we’ll have it and it will be preserved," MoMA director Glenn Lowry told the paper.
In many respects, that's also the museum's answer for its next steps: MoMA has made no decisions yet, other than the fact it is expanding. The plans revealed last month by Diller Scofidio + Renfro included only a handful of renderings, the visual language of which depended heavily on the scheme established by Yoshio Taniguchi in his 2004 expansion. The renderings did reveal the firm's explicit plans for the space that is currently occupied by the former Folk Art Museum building—an Art Bay garage-type space and a Gray Box gallery for performances—but that tells us little about the larger project.
Here's another view that gives a better sense of what MoMA might look like in 2020.

Now, there are some caveats to the Diller Scofidio + Renfro plan. Though the Folk Art Museum building's fate is sealed, this expansion scheme is far from final. "It's a damn shame to lose such a fine piece of architecture," writes Ned Cramer in a February editorial, "and all the more so because it is uncertain whether a Diller Scofidio + Renfro–designed expansion will ever get built or, if it is, whether it will be built to the architects’ specifications. MoMA is a notoriously tricky client."
But what we know for certain is that MoMA has prioritized its Midtown manifest destiny over a range of other options.
Those options include satellite institutions, such as the MoMA P.S.1 location in Queens, N.Y. (which is home to the museum's Young Architects Program). Perhaps a museum branch dedicated to 21st-century art in Brooklyn, N.Y., leaving the historical mission intact at MoMA's central campus.
Another option would be to stop growing. Over its history, MoMA has grown at consistent rates in terms of size and square footage. But there's a limit to the square footage that MoMA can achieve in Midtown. The St. Thomas Episcopal Church isn't going anywhere soon; the museum sold the property on which Tower Verre is being constructed, 40,000 square feet of which will be new museum space. The museum can't be made more dense with artworks without ruining the viewer experience—which is already troubled by high visitor traffic.

So perhaps there ought to be a natural limit to the number of objects that MoMA should even want for its collection. Museum officials (who supplied much of the data used to build the charts) could not give an exact figure for how many objects are currently in the museum's permanent collection. Suffice it to say, it's a lot—at least 150,000 works—among them the treasures of 20th-century art. Perhaps the greatest collection of 20th-century art in the entire world.
Needless to say, only a fraction of this collection can ever be displayed at any given time. And the museum's ambitions, at least insofar as the Diller Scofidio + Renfro plans have made them clear, run in the other direction: A good deal of the expansion is being planned with 21st-century work in mind. The Art Bay appears to be purpose-built for the kind of programming that has won museums and galleries long lines and critical derision in recent years—from the Rain Room at MoMA to Jay-Z's "Picasso Baby" performance at Pace Gallery.
Whether this mode of work will remain in vogue is difficult to predict. It's a risk to set aside so much space for a kind of artwork that could vanish—or more likely, be deemed too safe—in coming years.
Do we need a space at MoMA to see Blue Ivy Carter sleeping in a holo-cube—or whatever it is that performance art looks might like in the 2020s? Maybe. Do we need that gallery more than we need the first significant piece of New York architecture in the 21st century? Maybe not. But arguably, MoMA set these plans in motion long before the Folk Art Museum building was ever built.