Game Of Thrones: Is Gendry Really Cersei Lannister's Son?
1. The Jon Snow Parallels
If R+C=G, then it would indeed be VERY similar to the big reveal about Jon Snow's parentage. That might well be too much, but it would also fit with the parallels between them.
Gendry is, supposedly, the bastard son of Robert Baratheon. Jon is, supposedly, the bastard son of Ned Stark, who just so happens to be Robert's best friend. They both grew up not knowing their mothers. Jon joined the Night's Watch, and Gendry was going to do the same. They both have King's blood. Jon's closest relation is Arya; Arya was the closest thing Gendry ever found to family. Jon's purpose is to fight the White Walkers; Gendry claims he has always known he was waiting for something like that.
To borrow from another fantasy saga, there are elements of Neville Longbottom within this. Everyone assumes Samwell Tarly is the Neville of this story, but what if it's Gendry: like Neville to Harry, he meets all (or most)of the same criteria to be the Chosen One as Jon, but wasn't who the story chose to focus upon. Everything has been centred on Jon learning the truth, but that could be very deliberately setting it up for a big reveal of who Gendry really is too.