Update 6/28/15: Tyrese followed up with a new Instagram posted seemingly confirming his casting as a Green Lantern with the caption #TheOath has been taken. He also teased an upcoming announcement (possibly for SDCC) via an interview with Entertainment Tonight.
6/25/15: In an Instagram post, Tyrese Gibson (star of other lucrative franchises such as Transformers and the Fast and the Furious films) has hinted strongly that he may be soon part of an impending announcement to be possibly cast as one of up to two Green Lanterns in the new DC Comics Cinematic Universe. The fan art he posted also alludes to the possibility that Chris Pine may also be cast as a Green Lantern.