I personally love the look of JetBlue’s cabin and I am all for the narrowbody long-haul market....but the timings and frequency don’t match what is necessary for the LON-JFK market.
The current plan is for 1 or 2 flights a day from London to New York. If they go for LHR, that will reduce to 1 flight per day leaving LHR at 18:10. That just doesn’t work for many people and won’t worry BA, Virgin or any airline.