NFL Network's Michael Silver relayed the news Wednesday and added the Seahawks would "obviously be seeking a lot in return."
Silver also said the Seahawks will be "open for business" when it comes to dealing Thomas if they receive a trade offer that overwhelms them, according to NFL.com's Chris Wesseling.
The nuggets from Silver come two days after NFL Network's Ian Rapoport said the Seahawks "would like to do a long-term deal" with Thomas and "have him firmly in their plans for the 2018 season."
As an organization, the Seahawks are in the midst of a major personnel overhaul.
The team reportedly agreed to trade defensive end Michael Bennett and a seventh-round pick to the Philadelphia Eagles on Wednesday in exchange for wide receiver Marcus Johnson and a fifth-round pick, according to ESPN's Adam Schefter, and more moves could be coming this week.
Citing sources, Rapoport reported cornerback Richard Sherman "has told teammates goodbye over the past 24 hours"—an indication he won't be on the team next season.
According to Silver, the Seahawks plan to release Sherman within the next two days. He added the team would be open to re-signing him if the sides can agree to a more team-friendly deal.
Thomas, meanwhile, is scheduled to earn $10.4 million in the final year of his contract.
"I want to finish my career there," he told ESPN.com's Michael DiRocco and Brady Henderson in January.
"... As far as my future in Seattle, I think if they want me, you know, money talks. We'll get something accomplished. Other than that, I'm just taking it one day at a time."