OK, so that's what happened to the train from Pilar to Paso de los Toros... interesting. I remember public opinion was very much on the side of Argentina during that dispute, but from what you say, actions certainly have consequences... very few options left to cross into Uruguay, and Buquebus cleaned up.
For bonus points
I can confirm that the the same two-carriage trains that use to run the Pilar to Paso de los Toros route are now in operation across the Posadas / Encarnacion bridge. I was in Encarnacion a few weeks back, it's really very nice there. It could be an interesting alternative if you want a beach holiday.