They lost draft picks and their best player so I'm not sure how that helps them long term. Sure, they'll eventually get over it but it will have nothing to do with Kovy.
They dont have to pay that guy another $80 million or whatever it was. Losing the draft pick has nothing to do with him retiring, that was Lamoriello's fault for trying to circumvent the cap.
The Devils were not going anywhere this year, and now they are in position to make some moves next year. Kovalchuk off the books saves a bunch, and with Brodeur and Zidlicky both likely being gone, that opens up another 8.5 mil. They'll be able to make a splash or two in FA. So in the long run, its good to have him out of there.
....That is all not to mention the fact that they Devils are about $300 million in debt and looking for a buyer who probably doesnt want to take on an $80 million liability.