According to a video I've seen, the changes to scarlet monastery will remove the tabard. In Armory, after you defeat Herod, there is a stream of mobs that has a chance of dropping the Tabard of the Scarlet Crusade. Since that stream of mobs was not there, chances are the tabard will no longer be available.
Better get it now - if you want to make sure you get it. :)
We're going to look into this, as we feel that there are a lot of great items from the original Scarlet Monastery that we don't really want to remove from the Heroic version.