In addition, last I looked, PTC was still available on 900, 220, Protected Wifi, and BNSF has a track enforcement system for hy-rail working on lowband (45.16 or something like that comes to mind).
Last I recall seeing is that the FCC was not going to reallocate the 220 band for a railroad specific PTC control. frequencies still need to be coordinated with other existing 220 licenses on the same freq/band.
Amtrak is using ACESS in 900 on the NEC.
I'd wait a little longer before calling it "done".
Each transmitting wayside site still needs to be coordinated like any other radio site which may or may not receive its on FCC callsign. Typically the FCC lately has been given area authorizations with multiple locations, depending on how the application is submitted.
Our newer ones is the latter. One call, multiple freqs with locations for each service. Better tracking on our end on what is what. As licenses expire, this is the way we are going, logistically. Some that are legacy license's that have been around forever will be renewed the same way for the time being.
In my area, there is a PTC transmitting site every two miles, for over 800 miles. Each wayside signal is equipped.
If you look at the public ownership of PTC LLC, you will notice that KCS, FEC, UP, Amtrak, SCRX and a few of the other regionals are not owners or listed as part of.