No, its further north. The current section runs from Hopewell Junction, NW to just north of Poughkeepsie where it meets the bridge trail over the Hudson. I think the Duchess trail is now 12 miles. The bridge adds 1.3, then you can continue west in Orange County another 4 miles on the Hudson Valley trail, so a bit over 17 one-way.

The Maybrook rail line does run down to Brewster (from Hopewll Junction) and east to Danbury and Waterbury. I believe some of the CT. section is rail trail. I don't think Duchess County has any current plans to make it all rail trail as there might still be commercial rail use from Brewster (there's a link to Metro North) to Wappingers Falls/Fish kill, not sure though.
In theory, the line gets abandonded, they could link to the Old Put rail trail to the NCT/SCT.

I belive that Orange County intends to link/complete all the Hudson Valley trail SW to Walden. South of that the line is still running trains, but you could see a really long trail some day, like 50-60 miles one way.