Delta seems to have a "twilight zone" category for semi-cancelled flights. These flights will appear in the "Flight Schedules" search, and they will still appear in "My Itineraries" as "confirmed". However, they will *not* appear if one tries to book a reservation. Those flights are effectively dead.
Just yesterday, my LAX-MCO non-stops for January finally went into the "cancelled" category so that I had to rebook.
Looks like the surest way to know if a flight still exists for your dates is to try to book it for that date. If it doesn't appear, either it's dead, or it's sold out. Go to "My Itineraries" and check the seating assignments - unless the map shows the flight is largely filled, it's probably history. (I was the *only* one who had a seating assignment for either of my January flights!)
It's always possible that your original flights will reappear on the Delta schedule sometime in the future. The Delta CM on the phone wasn't sure if it would be allowed to switch back to those flights should such a thing happen.
