I'll go down now and state: the 787 will be the saviour and making of Manchester Airport.
Given that's exactly what the B767 was supposed to do before the world retreated to Alliance hubs I seriously doubt it. Remember any Jetstar punter flying direct to MAN is one less flying QANTAS. Not for nothing did BA sell Go, competing against yourself is seldom successful.
What Jetstar marketing want and QANTAS management allow are not the same thing. You can have hub busting B787s at MAN or a fleet of A380s at LHR, unlikely you'll see both.
Exactly what do you want MAN saved from? Looking pretty good from where I am and looking forward to flying through again in a fortnight.