TNA has a lot of talent that could be utilized in some shape or form for the WWE:
1) Samoa Joe-like signings for NXT: Austin Aries, Bobby Roode, Rockstar Spud, Magnus
2) Tag-Team signing: The Wolves
3) More Mexican talent to fill the void left by Rey: Tigre Uno
4) Retirement runs: Angle, Hardys, Kim, Mickie James, MVP
5) Repackage: Havok, Manik, Bram, Gunner
6) NXT Enhancement: Abyss, James Storm, Eric Young
In terms of others, I don't see Tyrus, Galloway, Mr. Anderson, Ethan Carter III, Awesome Kong, Taryn Terrell, or Low Ki getting another chance with WWE for awhile.
From the list of recent tryouts, I'd hope Athena, Havok, Taeler Hendrix, Biff Busick, and Johnny Gargano get signed.
WWE should hit up Bully Ray and D-Von to compete on NXT as they are doing with Rhyno. Both are well known and will entertain while the new talent continue to improve and become ready (Gable, Uhaa, Vasquez, Braun Stowman etc.)