Civ6 streamer and history PhD student @Paisley_Trees has together with a colleague interviewed @Andrew Johnson [FXS] during the CivGive charity stream last Sunday.
They discuss how they pick the civs in combination with making an interesting and balanced game, that they read the forums here (although that we need to discuss things earlier; although we had the right timing with Georgia), they discuss other leader possibilites in Civ7, and a lot more.
If you are really curious, you have to watch the video .