I disagree on two grounds:
We're still in the launch window and a ton of people are still on Normal. So early rares are going to be flooded. Not endgame equipment/lenedaries. The market is hardly settled.
Twinking was commonplace in D2. It was a means to get to the highest difficulty and end game. But at least in D3 you shouldn't see people twinking with duped items like in D2.