Rolling Stock M3A M7A Stations Valhalla Mount Pleasant Hawthorne Pleasantville Chappaqua Mount Kisco Bedford Hills Katonah Goldens Bridge Purdys Croton Falls Brewster Southeast this extending route will have 12 Stations Southeast Station
Extensions have been ruled out for a long time now and it's unlikely to change. Ignoring that, I can think of a few reasons why it is unlikely: 1) There is probably more demand for the Hudson Line or the New Haven Line 2) Harlem already takes about an hour to drive, making end-to-end runs less appealing. 3) We aren't long off the back of Harlem, and I'm sure most people would rather we had another US route, away from the Metro-North network.
I think the next us route will probably be the metro north Hudson line up to Poughkeepsie so they can include Amtrak.
Harlem Line express services to southeast takes about an hour as well. They run local after white plains to southeast so the time for a service to NWP and a service to Southeast is practically similar
