The only reason I'm led to believe this coin will be worth more is the description: "A gold coin minted by the three Grand Companies of Limsa Lominsa, Gridania, and Ul'dah to commemorate the reforming of the Eorzean Alliance. Guaranteed never to depreciate in value!"
If it's true that the events we're experiencing now will not be in 2.0, then it's likely this coin will not be obtainable either. Therefore I think the Qiqirn (or another npc) may pay more for it at that time.