The Penguins will now have the option to use a compliance buyout this weekend, which will help their current cap situation. Right now, at the time of writing, the Penguins are currently $3.2M over the salary cap.
In a recent appearance on NHL Network, Elliotte Friedman warned that Dubas doesn't like using buyouts, but would do so if it could make a Karlsson trade work. With their buyout window ending this today , the Penguins will either need to make a cap-relieving trade or use their buyout window if they wish to move forward with acquiring Erik Karlsson.