I'm thinking that the DL-operated ANC-SLC is the replacement for the recently cancelled ANC-SLC. As for the other flights, they may allow AS to redeploy the aircraft on other routes. The addition of a late LAX-SEA makes connections from the East Coast through LAX more possible. Knowing that there are late flights out of both LAS and LAX which arrive in SEA before 1am is very beneficial during IROPS.

Much like was done with SEA-DFW and AA, we can hope that AS will codeshare on the new DL flights to/from SEA and maybe LAX-BOS.