So I think TEB is the most likely candidate to be the subject of the upcoming campaign pack.
However, notice the problem, Tilea, Estalia and the Border Princes are not on the Vortex map. There are factions that could inherit their roster and mechanics (New World Colonies, Pirates of Sartosa), but since all newly added factions need to be playable on both campaign maps, the main TEB factions would remain unplayable in ME and you could only play as the aforementioned NWC and Pirates as well plus whatever the 3rd and 4th faction would be. It could be that the main TEB faction get split up and the 3rd and 4th are then moved from their Vortex starting positions to the mainland in ME, but that sounds rather awkward.
So any idea how they'll handle this?