That may not make any difference, depending on your locality. Unfortunately AT&T infrastructure is still relied on by others such as Sonic, which leases lines from the likes of AT&T fiber, at least in my locality.
I'm on the preorder list for Sonic, for the past.. almost 2 years now. In the meantime, I'm using resold ATT through Sonic. $10/mo more than ATT directly, but no MITM and no data caps.