Queen of Junk is going to be a Hero 100% sure. They did the same with Ana, Sombra, Doomfist, etc. They mentioned them very slightly by showing a Picture of them or a Backstory with them involved in-game or in a Comic. Hammond kind of the same but he might be the creator of a Hero like Efi was. The difference is that Hammond is mentioned/hint in-game on a Map. So he might become a Hero.
With Brigitte... i doubt she will become a Hero by 100 miles. First, they clearly show her on a Comic AND on a Cinematic and in none of them they gave her enough relevance to be more than just an Extra character for the OW universe to feel a little bit more alive. She is just a normal citicen.