The less legendaries, the better. Hope they don't introduce 100 new pokemon and 30 of them are legendaries, like usual...
This, fewer legendaries, already too many of them stuffing up the tiers. It's liek they are normal Pokemon which was kind of not the point?
Considering most of them have lower overall stats than Dragonite,Tyranitar, Salamance, Metagross,etc. the 600 BST total normal Pokémon, I think their rareness and the attached events or backstory is more the point than anything else.
This, the thing with legendaries isn't their numbers, it's their stories.