from the LAX FAX from the cheif pilot's office:
7ER AND OTHER RUMORS
Quite a few pilots have asked about a 7ER base in Seattle. Here is what we have heard.
Delta network planning is currently analyzing whether an ER base in SEA makes sense. No decision has yet been made, but know that SEA as well as other bases/categories, are being considered. For instance the company is looking into using the A-330 in east coast bases, the A-320 in SLC and the DC-9 in ATL. These are only examples and not an exhaustive list of what is being considered.
Also, know that any changes will only be made after a thorough analysis of the market.