Shift to another hub. Or, EWR has nonstop flights, which is a quick train ride from PHL; although the morning flight might not be "connectable" due to early departure time.

AS has nonstop flights ex-PHL, but not sure if UA is willing to transfer you onto nonstop flights on AS (or AA).

Bottom line here is there are a lot of options to minimize delays/cancellations. There is no need to go through DEN.