Key problem is it is over the dock and therefore requires an expensive civil engineering job to fill this in, hard up against the terminal, although the bulk fill material could be brought in from the river by barge.
Rather than fill it in, I believe they are looking at building a new apron on Stilts over the dock.
Are Swiss still getting some EMB170s? I know they originally wanted the aircraft to be LCY capable when they ordered it. Also, I believe LCY are talking to Alitalia (who have Emb170s) about launching services to City.
Fried Chicken