No they haven't I suppose, although it's strange they're dropping out a few of the gym leaders, but I have a sneaky suspicion they'll turn up, even if they're optional.
Besides, Lenora's replacement needs to be explained.
While thinking of gym leaders, wonder if they'll ever pull a typeless gym again? That was one of my favourite ones for being just wonderfully difficult as it's the truest test of your full team composition they can throw at you. I would've pegged Cheren as a candidate for that kind of thing, considering his background, but it seems not.