After seeing how the Burns-Karlsson experiment didn't work, i'm wondering why teams with an established #1 RHD are interested in Karlsson. Sens (Chabot), Washington (Carlson), and Fla (Ekblad) seem like square-peg>round hole fits because they have their top D already.
St Louis, NYI, WPG, Seattle, Minny, or Toronto are the only teams I can see that have a need at D, a window that will likely be open for the next few years, and are currently competitive. But even then, the cap dollars are hard to make work for those teams.
I just don't see how a trade can work even if we take a bath on retention, unless some major 1-1 like Karlsson for Marner madness breaks out