Not sure if I am missing something, but the Silvertown/North Woolwich branch has long been dismantled - so there is nothing that could be reopenend or something that could be rebuilt. In fact, the branch has made way for the new Crossrail section to Abbey Wood. My understanding is that to allow future development, there is passive provision for an additional station on that Crossrail branch somewhere near, but slightly east to the former Silvertown station. It would not solve the issue of a location off the airport, but it really would not be that far away (200 metres ?). As a public transport option, it would be quite attractive as it would, unlike the DLR, give direct access to Central London. My understanding is that passengers from 2018 will be able to connect to Crossrail by hopping on the DLR at LCY and connect at Canary Wharf - not sure if that is the final nail in the coffin for any future development of a LCY crossrail station.