Tempelhof supporters say they now have more than the required 170k signatures to initiate a "Volksbegehren" (local people's request to change a law) next. However they'd need a fourth of the local voters (that would be like 610k people) to have this accepted in a separate campaign. And finally it will not be strictly legally binding for the government. The mayor might have to change his mind as he has no alternative use for the place planned after the intended closure.
People living close to the airport are said to be the most ardent supporters of it's continuing operation in the recent campaign. Looks like the opposite of Nimbys there.