His management told the club on Monday that he wanted to pursue other opportunities.
"Given the considerable effort we have put into Dustin's development both on and off the field, and our efforts to retain him all season, we are extremely disappointed with this decision," Richmond general manager of football Dan Richardson said.
"We are proud of the way Dustin has developed as a footballer, and as a person, in his time at Richmond, and we have been steadfast in our view that he is a required player who has an exciting football career ahead of him.
"However, we understand the business of football, and Dustin's right to pursue other opportunities.
"We have also stated previously that we are determined to adhere to our payment strategy for all of our players, many of whom have already committed to the club and its future direction during the 2013 season."
I hope we throw everything to get him but with limited picks I doubt it’ll be happen. Have a feeling Collingwood will pounce especially if Thomas leaves.