With Bucksport gone, you're looking at rationalizing everythign east of Shaw Brook. Thats 61 miles GONE! If Rumford is closed you've eliminated another 25ish miles.
You've also cut something close to 15,000 carloads a year. Bucksport has got to be responsible for at least 1/3 of the traffic east of Waterville. While it isn't a knockout punch, it is a serious blow to revenue and profit. The rationalization of ~25 miles of track isn't going to recoup the loss of the mill traffic in Bucksport. It might not kill the company, but its going to show on the bottom line. And its certainly gonna make the ownership, which as discussed elsewhere is aging, reevaluate their commitment to the railroad.
I can't speak for him, but I doubt Newpy is suggesting the railroad is gonna go bankrupt, or just decide to not operate trains tomorrow. I think the point is, another loss on scale with Bucksport may be the trigger that sees the for sale sign go up in Billerica.