Hear me out here. So, the NEC is underwhelming right now. The route only has 4 stations (5 if you count the limited-stop Secaucus) and doesn't provide much variety. Now, extending the route would add commuter service and make it a more enjoyable and realistic experience. With Trenton to NYC, you could have the NJTransit NEC line and part of the NJCL. Plus, it would open the door for an extension to Hoboken from Penn due to some NJCL trains going there. You could also have the MNRR New Haven Line from GCL to NHV. This would probably have involve making the Grand Central line due to Penn Station access not existing yet (though it could be added once they complete it). You could also have a "game day" scenario with this, having the Yankee Clipper run from New Haven to Yankees-East 153rd. With the line being this length, you could finally add the Acela Express, making stops at New Haven, Stamford, NY Penn, Newark, Metropark, and Trenton. Now for the elephant in the room. SEPTA licensing issues. Up until this point I have neglected to mention the extension to Philly for that very reason. I think it could still be done without SEPTA by having some sort of stand-in service, like what they did with the Tri-Rail stand-in. It would degrade the realism, but it would be worth it if it is possible. If the length of this surpasses capabilities, perhaps a dumbed-down version from Trenton to Stamford could suffice. It would still allow the Acela to be added, as well as not having to end NE regionals at New Rochelle. The Grand Central connection could be eliminated by having non-drivable M8s that run up to Stamford. NJTransit would still be an option for those wanting to drive commuter trains. That's pretty much my suggestion. I would understand if this is beyond capabilities, but it would be a nice thing to see in the future.