I think people are forgetting that Eichel, while being the most valuable player in this deal in a vacuum, is disgruntled in Buffalo.
If this season, that challenged records for all the wrong reasons, isn't enough for Eichel to demand out, then it's next year. Buffalo has little to no rope with Eichel. Even though Eichel's under contract for the next 5 years, if he does ask for a trade and Kevyn Adams denies him, he could sit out, and his value would tank every day he wasn't moved.
It's a different situation in New Jersey where both players are happy and the team is in a better place. I can guarantee you no other team in the league would come up with two better assets in an Eichel deal than Jack Hughes and Hischier.
The only thing is Dahlin. Of course Buffalo would want to hang onto the recent 1st overall pick but the way he's performed up until now, I don't see his value being higher than that of Hughes or Hischier.
I think this deal is actually as good as it would get for Buffalo. Of course you'd rather hang on to Dahlin and only move who you're forced but that's how deals go.
However, this is as unrealistic a deal as they come. Pure fantasy from my view.