You would need to give up at least one of the big three and probably both Marner and Nylander, especially if there is any sort of guarantee that Karlsson would re-sign.
Teams would be offering individual players more valuable than that entire package and then supplementing them with 2-3 pieces comparable to those in your package, especially if an extension was promised. Think Barzal+'18 1st+'19 1st+B prospect that the Sens like. Think Draisaitl+Larsson+protected '18 1st+B prospect that the Sens like. Think Keller+Strome+protected '19 1st+B prospect. If there's no guaranteed contract, maybe ditch the B prospect. If there's a guaranteed contract, turn the B prospect to a blue chipper or another established top-6/top-4 player.
A comparable might be Marner+'18 1st+'19 1st+Carrick IF he does not have a contract. If he does have one, you're probably looking at dropping that '19 1st and adding William Nylander. Your offer is a crazy lowball.