The thing with television shows based on comics is that just because you get a character with the same name as one in the comics, you may not get the exact same character. We saw that in Arrow with Kate Spencer (Chelah Horsdal) who was the D.A. in Starling City until her untimely demise. She never became the Manhunter as Kate Spencer did in the comics.
So when it was announced that Robbie Amell, formerly of the Tomorrow People and cousin to Stephen Amell, got tabbed to play Ronnie Raymond in The Flash it seemed that we'd be getting Firestorm. But how long would it be before we saw him. Well, according to the shots below mixed with the fact that they are shooting the crossover soon, that's probably when we'll get to see the Nuclear Man. Though according to IMDB, Amell has only been attached to one episode so far, the third of the season called Things You Can't Out Run.
So now we just have to wait and see what the character is going to look like. The flaming hair should be interesting to see if they go that route. And of course the other big question… who is he going to be merged with?