If Kovalchuk was to become a free agent it would hurt in multiple ways. They would not nearly have the offensive depth and skill they would have with him in the lineup. It would also leave defenses with the opportunity to give Parise and Zajac more attention. With Kovalchuk they would have two dynamic lines. They also would then have too move Clarkson or rolston on the second line.That would mean the third line would also be weaker.
It still is unlikely that he does leave because he wants to be a devil for ever and they want him. If he stays which seems likely they will have a great chance for the cup.