Chelsea could watch one of their star players join one of their London rivals this summer. There are likely to be quite a few exits at Chelsea this season, largely because of profit and sustainability rules. Thiago Silva‘s departure has already been confirmed, while there are doubts surrounding the futures of Conor Gallagher and Raheem Sterling. Gallagher’s contract is running down, while Sterling has been linked with a move to MLS. The Blues will definitely be one club to keep an eye on during the summer transfer window. Three London clubs want Chelsea starSilva, Gallagher and Sterling have a…