It's probably about the money
I suspect so, given that I recently read that the going rate for public IPv4 addresses is around that much, although with some research it looks like that depends on quantity. This site (»tradeipv4.com/) is quoting a single figure of $8 (that's for a sale; $1/year to lease).
Maybe that is the key here, getting another $15/month?
So AT&T gets to repurpose a large quantity of valuable addresses and you get to pay an additional $15 per month for the privilege of getting the same level of service you've been getting since you got your connection from them.
This would be in character for a company who's CEO in 2006 ignited the Net Neutrality firestorm with some fantastically ill chosen comments (»www.businessweek.com/magazine/co···8092.htm) ; among other things it was estimated this cost AT&T a billion dollars when they later bought Bell South....
It could also help explain how people are being forced to "upgrade" to U-verse DSL from plain DSL. I'm stuck with plain AT&T DSL, if they extend this policy/architecture to us I won't like paying nearly 50% more to enjoy the same service.
(Why do I stick with them? Not even sure if the local cable monopoly will serve us and AT&T's service is rock solid for me and my family in this town.)