I too was disappointed finding out that we weren't getting disks by mail any longer. However, if you still like the service you can still get it, just separately. Like others, though most of the movies would eventually show up somewhere on BAH (I get the Starz package too) there's no substitute for watching a movie without video and audio compression. For some movies doesn't matter, but for many movies - for me - it does.
Here's a response to an email I sent stating my disappointment and asking if the service would still be available:
Thank you for contacting Blockbuster at Home.
I understand that you still want to continue receiving titles in the mail through a separate service. Let me assist you with your inquiry.
Since you still want to enjoy getting movies and games by mail, I have forwarded your account information specifically your email address email@example.com to the appropriate department. You will then be contacted with an exclusive offer and receive an email shortly after September 19 with instructions to have the separate service.
Should there be any additional concerns, please let me know.
note: of course that's not my real address.
Here's a link to the Blockbuster by mail site if your interested in looking at packages.
Update: Just got my email from them which looked it was just adding my email address/login to the mailing list. Looks like because I was a BAH member, I already had an account: I was able to use my BAH login on the Blockbuster.com site. Not only that, but it actually has all my queue information as well. No repopulating my queue for a new service, very pleasantly surprised. I've currently got a two-disk at a time package, not what I'll be doing - dropping the service, staying with 2DAT or go to 1DAT. I'll wait to see what they offer for a package come the 9/19 email.