Which AT&T DSL product? There are two:
AT&T Worldnet DSL, which is not as fast, or inexpensive as Bellsouth FastAccess.
at&t Yahoo! HSI, which has comparable speed tiers to Bellsouth FastAccess, and at a lower price.
AT&T Worldnet DSL Service came with the AT&T brand when SBC bought AT&T. It is, primarily, a CLEC service, often served up over Covad lines.
at&t Yahoo! HSI was, originally, SBC Yahoo! DSL Service; renamed when the company was rebranded from SBC to AT&T. It is an ILEC service, similar to Bellsouth.
Considering that SBC was formed by the purchase of Ameritech, Pacific Telesis, Southern New England Telephone Company, and Prodigy by Southwestern Bell Telephone Company; and that all of those service products were unified under SWBT guidelines (SWBT also rebranded to SBC), my guess it that AT&T Worldnet will continue to be offered where AT&T is not an ILEC, but at&t Yahoo! HSI will be extended into Bellsouth as a replacement to FastAccess.