My read on Pennsylvania state politics is that the rail service focus will be on addressing the maintenance backlog at SEPTA for several more years. The legislature has until recently been gerrymandered in a manner such that non-Philadelphia pro-rail forces don't get much representation.
After the 2020 redistricting is finished, which should eliminate the pro-Republican gerrymander in the state legislature and make all the seats more competitive, as well as transferring a lot of seats from the countryside to Southeast PA, I think the legislature will pay more attention to service beyond Harrisburg; so likely after the 2022 elections. The reasoning here is that right now, all the pro-transit representatives are caught up in dogfighting to provide the necessary service to the Philadelphia area; when there are fewer knee-jerk anti-transit representatives, the legislative consensus on transit will be able to be more generous to the whole state.
SEPTA still has a very large backlog of work to do (more than 70 regional rail stations need ADA upgrades, and the trolleys all need replacement for ADA reasons among others), and PennDOT is still working on the Harrisburg Line station replacements, but I think that around the time when the trolley replacement gets funded, the Harrisburg Line station replacements are all under construction, and City Hall subway station ADA work gets finished, the legislative mood will turn towards providing some transit to the rest of the state. That's probably when we might see serious work on increasing PGH-PHL service. Although we might see an effort to bring service to Allentown/Bethlehem or State College instead.
I don't know what the rail freight situation will look like at the point, but I can tell you it won't have any significant coal traffic.