In both cases, either trading Zibanejad or signing Panarin, you're doing artificial things.
The idea that Gorton has followed so far is to get young assets with long term potential for those without a long term future here. Zibanejad is a young player on a great contract. He's part of the future. He can lead our youth for another decade, and when he does require a UFA contract, the team will hopefully be contending, so the best (early) years of his UFA contract won't be wasted on a rebuilding team.
Panarin and Kreider will be on UFA deals and most likely will live up to their money (if ever) early on when the only thing it will achieve is to drop us from #2-5 to #10-14.
Then, when Kakko, Chytil, Kravtsov, K'Andre, etc enter their prime 4-5+ years from now, the contracts of Panarin and Kreider will be anchors preventing us from signing young(er) UFAs at that point or preventing us from re-signing our own guys.
You don't throw money at star UFAs when the most talented guys on your team are 18-20.