If a trade has to be made, Carolina seems like the best potential partner from Ottawa's POV.
• 2nd overall pick
• High-potential young defensemen that could be included (Hanifin, Pesce, Bean)
• Young, cheap forward assets that could step into our top 6 next year (Teravainen, Lindholm)
The best case scenario for use would be:
Karlsson for 2nd overall, Hanifin and Lindholm.
You could then take Svechnikov at 2, Dobson/Bouchard/Hughes at 4 and go build around a young core of:
Duchene, Stone, Chabot, Svechnikov, Hanifin, Dobson, Lindholm, White, etc.
Unfortunately, I don't think that's realistic from Carolina's end.