SF is far from being a reliable source.
Maersk has its North American headquarters in NJ and fills a considerable part of SK’s flights CPH-EWR. There will always be some SK presence at EWR.
It’s possible ARN/OSL might move to JFK but it’s uncertain whether SK will get slots there.
Remember that SK flying to EWR predates CO merging with UA and the latter having a hub at Newark.
The source may not always be reliable, but it is an accurate representation of what the CEO of SAS said at a conference.