A CBA is needed first to consummate a trade, so assuming that happens and the season starts in the near future, this Garrioch story titled - "Pittsburgh Penguins Look To Bring Back Ottawa Senators Defenseman Sergei Gonchar", may be relevant:
"If the NHL does start a shortened season next month, don't expect Sergei Gonchar to finish it with the Ottawa Senators. The veteran defenceman, going into the final year of a contract paying him $5.5 million per season, will be targeted for a trade by the Pittsburgh Pengions once a collective bargaining agreement is reached. Whether Gonchar's former team waits until whatever date is set for the trade deadline or makes a pitch before the season begins isn't known, but league sources say Pittsburgh GM Ray Shero has interest in bringing back the 38-year-old."
I missed you "league sources".
Now this isn't the first time Garrioch's written a Gonchar trade story, there have been a few: