In my opinion, the worst outcome on Nikishin's side was sitting an entire NHL season and ending up exactly where he already was. A 10.2b player with zero leverage.
By signing for 1 season, as andyt noted, he will be a full RFA with arbitration rights AND offer sheet eligible. If he isn't traded before next July 1st, he won't need to rely on the Canes to find an acceptable trade anymore. He and his agent can try to get a contract from any team he would want to play for, unfettered by the Cands working out a trade.
With the Canes of course, this could play out multiple ways from here. He could play out the season, here, get to July 1st, and spend the entire summer trying to find the right offer sheet. We also could trade him at any point before the deadline or after our season ends.
Now, this is officially against the NHL CBA rules, but I would not be surprised if the Canes have a handshake agreement with Nikishin that if we don't trade him before the deadline, we will trade him in the offseason OR that we not match any offer sheet he signs after July 1st. (sory of a hush hust wink wink handshake agreement that is technically illegal but only if you get caught).