It would be good if Shelley and Charlie Jnr did return, but i'm not sure if Sally Lindsay has agreed to come back, plus we don't know if Tracy's trial will be shown on screen.
And if Tracy admitted she was guilty, would there be any need for a trial? I remember they did this with Chrissie Watts in Eastenders. There was never a trial for her killing Den, and it was presumed that as she admitted the crime and admitted she was guilty, a trial wasn't needed. Could this happen with Tracy? If so, Shelley may not need to return to be at Tracy's trial..