I believe the Shay is still in Croghan, along with one or two other pieces of rolling stock.
I've been told that one of the 44 tonners is in the engine shed in Lowville, but cannot confirm that. There is a 44 tonner in use by the MA&N at Carthage, but I'm not sure where it came from. It might be the other L&BR engine.
The only use of the Lowville line these days is car storage.
The C&A is also used for car storage. There are a couple of industries switched in Carthage itself, including Slack Chemical. Talk continues of resuming rail service to Newton Falls, but the paper mill is kaput.
MA&N has been serving an industry in Lyons Falls, but I don't know the current status. On trips through the area over the winter I never saw any evidence of rail activity there. They do go to Boonville on a regular basis.
Does the MA&N still use the branch between Lowville, Carthage and Newton Falls?
Point of order here - the line between Lowville and Carthage began life as part of the Utica and Black River (thence RW&O and NYC). The Newton Falls line (C&A) began life as the Carthage, Watertown, and Sackets Harbor, or an extension thereof. I believe the intent was an east-west line across the Adirondacks. The mileposts are numbered from Sackets Harbor.