It has been my personal experience that when UVerse enters an area, traditional DSL has disappears.
Yes, that is true, AT&T would mark an area as not qualifying for DSL if there was Uverse in the Area, but this practice has been in-consistent.
There are locations where we have ONUs in the building with available DSL circuits and they refuse to sell it to us.
Yes, we have seen that too, not sure what is the official reason, but in system show the Remote DSLAM being out of capacity. 
I'm sure this is true, I know we have requested service disconnections more than once in the past and have had the account closed, but DSL has remained on the line. Plug in a modem and you get sync, type in a user and password for another site and you are surfing... I hope they don't make it a habit of leaving circuits up for non paying customers. That a lot of unused service going to waste.
On another note, they sometimes try to offer us a 768k connection in a place where we currently have 6mb DSL service.
There has to be more context to this... a lot of DSLAM they are or have quietly turned down backhaul capacity, as such new circuits are only for lower speeds.
One more thing, once you get UVerse, you have to forfeit your
traditional DSL. Apparently, the two services cannot coexist (some
billing program issue),
Yes that is correct ...
what makes it worse, if you suddenly realize your 6Mb was replaced with a 768k UVerse, there's no going back.
That does not make sense... there is no such thing as 768K Uverse...
(Uverse starts at 3meg down, 768K down is called DSL Lite.. )
That's what I thought, but not the case. This is especially prevalent in the South Miami area. One think I know is that the service was labeled "UVerse" not "Fast Access DSL", however, I cannot tell you if the underlying technology is ADSL or VDSL2 (we went running to the hills after 768k). The justification they gave us for the lower speeds on the "UVerse" service was that they were in the process of transitioning their existing DSL service to UVerse, and until that was complete, the backhaul capacity was not going to be available. I still don't believe this... Does not make any sense to me that they would have to wait for everyone on their old service to switch to UVerse before they make the bandwidth available. Its ATT, I have a real hard time cutting though all the layers of junk before you get to someone that actually tells you the truth or knows what's going on.
If you can avoid the ATT hassle. Try looking into wireless providers.
Agreed...
WiMax has come to the rescue many times when the Cable and Telco companies have not been able to provide us with the service at the price point we were looking for.
Agreed..