User blog comment:It's Good to be the Queen/Gwen vs. Morgana - 1st Face Off, season 5/@comment-4650675-20120330073345/@comment-74.128.196.205-20120330095207

Morgana would get the throne only if Arthur dies without a legitimate heir. That would the only time illegitimate children would be considered, but Morgana has been so vile they would go to a kissing cousin twice removed before they take her. That why Morgana tried to take out Gwen, if she and Arthur have a child, it's all over. Besides, in 4x02 when Arthur and the knights went on the quest to close the veil, he told Agravaine shold the king die and he doesn't come back, Agravaine gets the throne. (That's why I expected a triple cross from Agravaine.)

As for Morgana's past Gauis put everyone in the loop.