They still own the character until the end of 2012, so she can still be used for at least a year and a half.
That really depends on what the heirs intend to do with the rights. The most obvious guess is that they expect DC to buy them back and cash in. Beyond that it's anyone's guess what they're going to do with a Superman who can't fly, doesn't have the 'real' logo (the current S-shield was introduced after AC#1) nor features characters like Lex Luthor and the Kents.