We are getting three 767-300s from Hawaiian. Acceptance is supposedly in a month or two, but not hitting the line until 2019.
I’ve heard they are three additionals, two additionals plus a fill-in for one to be retired, and I’ve heard they are ALL replacement aircraft. Who knows.
The reason for keeping the fleet: they fill a need that can’t otherwise be met. This might be aircraft performance metrics, new aircraft manufacturing backlog, or capital expenditure reluctance.
I wouldn’t be surprised to see the P.S. airplanes go...they are the oldest, non-ETOPS, and used only for coast-to-coast domestic. Other airplanes can fill that niche. But that is only 15 jets.
I think the 756 fleet as a whole will soldier-on until we see a 797, more 787s, or maybe a 321/330 NEO.