As far as I’m aware that flight has never had new F and isn’t currently scheduled as a new F route, so I would assume you will be in old F. There is always the possibility of last minute changes but I’d also put that at close to zero here - given the plane continues to EWR after ATH, EK is locking up a frame for almost two days by putting it on this route, very unlikely they’ll do that with a new 777 when there are much closer places they can send it. I don’t imagine the kind of passengers willing to connect in ATH when there is a direct flight are the high margin kind that would justify it also, unlike some of the direct flights to the East Coast.