What we don’t know is how this plays out. Does the Modern Era end, and then every player must compete to achieve a victory before the other players? Can players who did not yet complete a track still outcompete their rivals and complete the victory first?
So no, I don’t think this indicates there is a whole new age (with all the units and civs such a thing would require). Rather, there may be an endgame period where you can lob nukes at eachother while someone desperately tries to build the World Bank.