Discontinuing Amtrak's long-distance services -- which are clearly not competitive in terms of ticket price or travel time with alternatives -- comes up time and time again, by members of Congress and commentators alike.
However, successive directors of Amtrak have always opposed the discontinuation of long-distance routes. Congress could likely force the issue, but it's interesting that Amtrak leadership always leans in favor of them.
There are some routes in the northeast that Amtrak turns a profit on [1][2][3], and some others are subsidized by states enough to still make them worthwhile to operate (CA, IL, NC). But if the long-distance routes were defunded, they'd likely never come back under the Amtrak banner, and significant layoffs would ensue.
[1] https://news.ycombinator.com/item?id=15968720#15976146 [2] http://reasonrail.blogspot.com/2012/12/amtrak-routes-by-2012... [3] http://www.riarp.org/blog/2014/11/25/september-amtrak-report