I will be very surprised if this game does arrive in 2015, almost all big titles are delayed nowadays and since its a very early window of Q4 2015 it could well gets a spring 2016 proper release date that then gets delayed to late 2016, the most important thing is they do not do a ubisoft and rush it to market broken.
Personally I am fully prepared to see the final game launch in mid 2016.
It would be nice if it came out in Q4 2015, but I just doubt it considering the scope and quality the team wants to achieve. I just hope The Investor will be understanding 
I understand your estimations but please keep it for yourself and believe in the Warhorse team. If the goal would be later it would take even longer just because of the psychological effect.
So dear Warhorse developers, we all do believe in your skills to finish the game until the end of 2015!