I see that the 2 flights (174 & 112) are scheduled to depart JFK within 25 minutes of each other. About time they used an A380 on this route, perhaps?
Aside from frequency and the limited number of 380s BA have available there's also the minor issue of the infrastructure of JFK Terminal 7 (the one BA usually uses). FWIW from an airframe drivers POV many of the gates there are physically an
extremely tight fit for a 744 or a 772/773, and the last time I was there it was one single level air bridge per gate.
I think to get JFK T7 (at least the side BA use - the low numbered gates) and the surrounding concrete, blastwall
and other infrastructure up to A380 standards would require considerable investment and the business case probably falls in favour of the existing arrangement.