Defiled Augment Runes after 7.3
I've heard this new item will take a few weeks to get, it requires exalted with a new faction.
People are still progressing in ToS so there will still be demand, and you get better gear from open world content on Argus so LFR participation will likely go down.
In this expansion the most sold item is Defiled Augment Runes. for me . Sold thousands of it. Just flipping them in th AH. Avg . 200gold profit/unit.
In my opinion still profitable after 7.3 and i will do . (1-2 week more) ;)