I do not expect cancellations with the exception of weather related incidents. When Frontier first pulled out of Philly they went to Allentown....touted it as a low cost alternative for families traveling to the Orlando area from Philaldelphia. Though it didn't take off the way they hoped and they ultimately pulled the service, they carried out all of the already planned flights. They are only accepting reservations July-nov .... So I imagine this is a test as well, and expect them to keep all the currently scheduled flights.
When they pulled out of Allentown, they went to Trenton and have been successful there I believe, having a friend who has flown that way a few times. Interestingly, Trenton is having some runway work done this summer, right around the same time the flights start in Wilmington.....so I think this may also be a re-routing of those flights too. Philadelphia manages a lot of Delaware and southern New Jersey air traffic, so I think generally speaking a net is better cast in Delaware or Trenton as opposed to Allentown....that's a long drive from Jersey.
Now I am no expert by any means....those are just my thoughts. I for one hope this route sticks!!! Mile wise it is probably 6 & 1/2 to either Philly or New Castle, but NC is certainly easier for many reasons!!