One-way D1 Z fares on JFK-LAX currently go for $1600. If there is not Z currently open on flight, they could open up some as flights gets closer. If there is already Z open, then the $1600 each-way price point is likely the lowest you will see on route (unless they file new fare filings which is not all that likely). DL has 5 fares classes for D1/FC fares -- J/C/D/I/Z with Z being the cheapest and J most expensive. It looks like for late April, they currently mostly only have I inventory or higher open on flights. I fares go for $2400 each-way. So it's not unreasonable to think they might open up Z on more flights as dates get closer. But the higher demand flight times on this route will likely never see Z open up.