Should be able to roll Eichel and Glachenyuk down the middle at the Olympics come 18, so there's definitely room to hope from a pure skill standpoint. Though 18 MAY be just a bit early in their careers to expect top 6 roles in a best on best out of them unfortunately.
Really not much down the middle going forward right now that looks that good at the moment.
Galchenyuk will be 24 at that point, which would be a perfect age for him to be in the top 6.
Eichel will only be 21 so for him I'd say he'll be too young.