I found the same thing when searching on that. I think they're referring to another "someday" path on the Bronx side of the river.
Again when I read it I thought why not extend even further down. There is a "corridor" because the Metro North makes it down. You could go as far down as, and kind of connect up with the Willis Ave Bridge. There are a couple of squeeze points that would have to be worked out but mostly there is room. Would pass though a bunch of parks too.