Another missed train question -- looking more recent policy / experience

Have a flight into EWR and upgrade cleared but meeting moved to PHL. So I thought, still go to EWR and take the train to PHL. Have taken many NE Corridor trains from EWR in the past but never Amtrak. In fact it has been years since I have ridden any Amtrak,

So I booked a EWR-PHL reserved Coach seat, somewhat tight connection 40 minutes which I think is doable but figure I would just catch the next train in an hour later if I miss the booked train. Apparently it is not that simple but not sure what I need to do if I arrive to late.

I will (hopefully) have internet on the plane if seriously late and of course a cell phone.

So what is the process today if you miss your train at EWR?