I don't know how accurate salary reports are, but my feeling is it is sustainable in England. For the top clubs anyway.
TV revenue is massive, and ever increasing. Add that to brand commercialization and sugar daddyism and the top clubs are pretty comfy.
Besides Ashley Cole in his prime was an elite English footballer. Can't be used as a yardstick to judge average player salaries. I wonder how much Totti for instance is earning, or was earning a few years ago.