Although i hate this game from the bottom of my soul, i'd say if there is one place i'd like to see, that'll be Akavir
I know it isn't in any of the previous games of the series, but the Akaviri culture really intrigued me very much, so mysterious.
A lil Off Topic, if theres any person i'd like to meet, i'd say i can't wait to see Talos/Tiber Septim.
I hope my lore knowledge is accurate, but Talos is around in 2nd Era albeit at late 2nd era right?
Trust me, the only reason they(Akavir) seem so interesting is because we do not know much about them and they pretty much exude mystery. This leads to speculation on our part. If we actually saw them made by developers one day I doubt they would live up to the hype. While it would be cool the mystery would be over and the interest would quickly fade.
Tiber Septim was active at the end of the 2nd Era. However the MMO seems to take place several centuries before he would be alive. A part of what will become Talos may be alive in the Underking Wulfarth though at this time. In fact around the estimated time of the MMO the Kamal Invade from Akavir and Almalexia and the Underking Wulfarth essentially take out their leader.
That's as far as I know. Idk though too much because I'm a little drunky...