LBA-JFK will never happen at Jet2, it is going ahead in the form of a charter programme for next christmas again but nothing more than just a couple of flights will ever materialise.
Should long haul happen at Jet2, it will be from MAN to start with, however the first routes flown on the 767 will be from LBA due to the large Jet2 infrastructure available at LBA to get 767 operations up and running.
This is assuming the aircraft do actually come, 757's have been rejected in the past due to their condition so we may see the same with the 767, also baring in mind if its a Rolls Royce bird (maybe ex BA/QF?) there may be some further performance issues from LBA. Time will tell but exciting times ahead at Jet2.