Amtrak DOES still use the F40s, I think. If I recall correctly, they were being renumbered into 5-digit locos, and being used as Cab Cars on short distance lines like the Hiawatha (Chicago-Milwaukee/Madison). If the F40's were being sent to Metra, then there would be less need for their Motive Power (MPI) engines.
Also, I think I read in Trains magazine that AMTK has just started overhauling Superliners, and purchased some new Genesis engines. However, they seem to be doing just fine on power these days. Unless they bring the Pioneer back... ugh. That would be a waste of money. But the Desert Wind would be nice.
Correct me if I'm wrong on any of this. I'm a kid. What do I know?
Steve