It was far more than just trailers and tech demos. According to reliable sources Nomura had finished writing the story by 2010 and the game was supposedly 25% finished and planned for release on PS3 in 2014 as of the 2011 trailer, but shortly after that Square was shown an early PS4 demonstration, and Square's CEO Yoichi Wada made the decision to transfer it to next gen and turn it into FF15. After that, Square wanted it done as fast as possible, so Tabata and his team were brought in to help with Tabata co-directing. There are reports of Tabata and his team clashing with Nomura and his team, so eventually Nomura was dropped entirely so he could work on KH3 and FF7 Remake, which had both entered early development by that point (December 2013).
Except that the story he finished was mostly what we were shown. Nothing Nomura made diverged significantly save at the start. The only differences were the insertion of the Oracle role and the growth in Ardyn's role which was originally an Emperor thing. Well, there was also Lupus, but Lupus was no different to Ravus in anything excepting design.
Women can be manly too! Have you seen the internet?
Yes, we stressed that if more women are needed somewhere, it's in K-dramas.
Epic was right all along...