Yoshida says a lot of things, that doesn't mean what he says is the reality. Their balance team literally kicks people for being too good at the game when it comes to non-ultimate content, what makes you think it is remotely believable that it's going to be 'harder than any other expansion before?' To who's standard? To people who would regularly clear savage on patch, or to people who can barely handle pressing a single button that would help the party?
Especially when he already said that there will never be another Thordan EX, that TG Cid was nerfed into the ground, and other, countless examples in casual content (some are good, like being able to revive on Titan) on why what he said is more than likely a statement to appease people who don't know better? People have been here for ten years, or even longer in my case, and while a lot of what he said is good thought and has been followed through, he is not reliable when it comes to how hard content will be since he honestly doesn't know as far as anyone is aware.
Don't believe what people say immediately when the proof is searched easily through youtube that it is not the case. It isn't even close.