Let's be real -- Blizzard very rarely goes back on the ideas it floats and this is a fairly uncontroversial change so I'm all but certain this is how it'll ultimately be implemented.
Regardless, this is the easiest way, imo, to keep the PvP seasons from being weird while still fixing the itemization issues that they had with ToC. I mean, fuck, I guess another alternative would be to inflate Naxx/Ulduar item levels then remove ToC altogether but... I don't know how well that'd go over.