Officially, the Seahawks still have Jacob Martin and Bakevious Mingo on the roster. Unofficially but more real, they are both gone and Jadeveon Clowney will be a part of the team. Seattle made a lot of moves today and finalized their 2019 roster while making a major trade for Clowney.
As it stands right now, Seattle has no backup quarterback for Russell Wilson. Geno Smith was designated as a Terminated Veteran Contract and is not on the team but Seattle will likely work out a deal to bring him back. Paxton Lynch was waived unsurprisingly, so Smith is the likely backup.