Well this is one I really need to look in to as it will more than likely affect me and the family over the coming years.
Whilst I agree that it is a bottleneck I can’t see where the land that may be needed will come from. London Reconnections did an article showing the possible changes that could be made. https://www.londonreconnections.com/2015/east-croydon-revisited/
Whatever the decisions made it will inconvenience many people for a long time until complete.