Something else I stumbled on recently is that the city and CSX are fighting about the value of the remaining piece of the Putnam Line from Van Cortland down to 230th street.
The idea is that this could extend the trail, and also potential "daylight" Tibbets brook and keep it out of the combined sewer system.
One interesting proposal is at
https://static1.squarespace.com/stat...Putnam-web.pdf which would basically extend the path down to the Marble Hill Target, and build some park there and an interface to a theoretical riverfront path in the Bronx.
While they don't mention it, seems like that could connect to the Broadway bridge, too.