They moved him to the OF because of his speed. He struggled for years to learn the OF. They never even hinted at moving him back to 2b. Would he ever move back to the IF? It really doesn't seem like it to me.
It seems unlikely that he's going to be moved in a trade TBH. I think they are just stuck with a weird 4 person OF rotation and wind up sitting Masa in favor of the 4th OFer a lot. If a contending team gets a significant injury, maybe Duran would be dealt? Prior to the season, Abreu is more likely to be traded than Duran IMO, but seems less and less likely as we get closer to players reporting.