Ever since New York’s Dia Center for the Arts announced that it was abandoning plans to renovate a Greenwich Village industrial space into 45,000 square feet of exhibition space, observers have been wondering what the Dia’s long-term future is, if any. “We need Dia, and Dia needs to do something decisive soon, even if it’s only to open a temporary space.” Meanwhile, buzz is continuing to build for the arrival of the New Museum, which has a $50 million home under construction in the Bowery.