I know that agendas are out of play and can't be affected by other cards normally, but one thing that FFG stated was they wanted agendas to be more optional based on what you may see other decks have.

Do you think this means that there may be cards that allow you to unattach these agendas(your own agenda) so if you now see that it fuels your opponents abilities you can have that flexibility?

For example, perhaps I decided to kill Quentyn Martell and make him an agenda. After this fact, my opponent plays Northern Cavalry Flank. "If an opponent is running an agenda, Northern Cavalry Flank does not kneel to attack."

Perhaps there will be some way to remove a character as an agenda to make NCF less powerful after the fact.

I don't know, I'm bored and want to stir up conversation!

I think it is more along the lines of they may choose to put more character agendas into the mix at some point, then you could potentially run multiple charagendas in your deck and choose to attach the one which will give you the most benefit.