Kelly: Ms. Kline, how do you think the attempt on Detective Alex Murphy's life will affect tomorrow's vote for the Dreyfus Act?
Kline: At this time, Omnicorp's sole concern is the full recovery of Detective Murphy.
Pat Novak: How many times does Detective Murphy have to give his life for his country?
Pat Novak: I sincerely hope the Senate makes the right vote tomorrow so that Alex Murphy's sacrifices will not have been in vain.
-- Robocop 2014
I was wondering why will not have been is best used here. Why not will not be or have not been? Is will here auxiliary or epistemic?
Is it the same usage as in:
I will have completely finished by next June. (usage of simple future perfect, auxiliary)
It’s no use phoning - he’ll have left by now. (used to express certainty about the past, epistemic)
or a variation of either of them?
I would think it's associated with both usage here - Murphy's sacrifices refer to the past while being in vain or not refer to the future.