I'm all for Eich, but here's a trade that is doable, but bad for Sabres (I think):
Buffalo gets 1st overall from Edmonton
Phoenix gets Reinhart and Buff' other 1st in 2015
Edmonton gets Eichel, Phoenix's 2015, +pick or player
Phoenix might need and additional incentive (Buffalo's 2016 1st instead of the other one this year). Edmonton would get Eichel and Hanifin + which makes sense. Buffalo gives up, essentially Eichel, Reinhart, at least this year's other first (maybe more), and likely something additional to Edmonton (though I honestly believe Eichel + Hanifin >McDavid).
I think it works for everyone except Buffalo, so I wouldn't do it. But it could be done