I'm sure when the Co-op (i worked there during the last Christmas it was open) we're deciding what to do before the closed the department store section and just kept the supermarket, they was talk of turning it into flats aswell as another department store etc. However, NCC had changed there policy towards apartments and that effectively ended that possible scenario.
Also the render of the glass front and possible demolition is actually the least probable thing to happen as the building is listed, is a huge building and doesnt happen to be in a little accessed area of the city, where arsons of buildings have occurred in the past.