Depending on when your flight is, that is pretty much impossible to tell. Equipment can change any time, and obviously, the further away the trip, the more such a change is possible, even though at the same time, the further away the trip, the more planes get converted so the lower the odd that old 777 be used, but it still won't be impossible for quite some time regardless of what is currently scheduled on your intended flight.

It's a short flight, so maybe not the one on which I would be most tempted to go for F personally. However, one question i would have is whether you have any status with AA? In F and the new CS J, pretty much all seats are good. In the old CW, however, not so much, so unless you want to pay for seat selection, J could be a bit more of a risk.