If Blizzard wanted to stop model editing, they wouldn't have to ban all of their customers that do it or update their warden program. They can easily make it so that WoW no longer loads custom MPQ files, which is just what they did in the Cataclysm Alpha. This doesn't mean that they will do that once the expansion gets released though, because the same thing was done during the WotLK and the BC alpha releases.
So long as you don't use it to exploit, like changing saronite veins to, say, ragnaros, then they will not ban you.
Stop scaring people. Simple Model Edits are safe.