Karlsson, Panarin, and Seguin are all elite players. This isn't a Richards, Drury, Redden, Holik-type situation.
Every team in the league has guys that they overpay. Every team that has won the cup in the salary cap era has had a couple bad contracts each. It's not the end of the world as long as it's not too widespread. I'd rather overpay a million or two to difference-makers.
I also think that the impact of these players is being a little understated. They are able to produce in the face of tough competition, AND push other players down the depth chart, into positions in which they can succeed.
Looking at Karlsson, for example. Yes, he's going to get a huge contract. But, he's orders of magnitude better than our best defenseman right now (Skjei or Shattenkirk). He also pushes Shattenkirk down to the second pair, where he's much more likely to feast on the quality of competition he'll see there, versus the top competition he'd see on the first pair.
Karlsson
Shattenkirk
Smith/Pionk/DeAngelo
is worlds better than
Shattenkirk
Smith
Pionk/DeAngelo
Elite players have positive ripple effects throughout the lineup, and throughout the course of games and playoff series. I'm not advocating trading away the farm for these guys, but it's an absolute no-brainer to throw a dump truck full of money at them if they hit UFA.