At first glance this does look like a terrible deal for the Islanders.
Is there the possibility that the Islanders got permission to talk to Vanek prior to this deal, to get his reaction and whether or not he might be inclined to sign with the Islanders? If so, then there might indeed be a very good chance for him to re-sign there.
I would say that the money situation argues in your favour. Next year, the Islanders will have just $28 million in available cap space, with only a few UFA's and RFA's (aside from Vanek) like Nabokov (assuming they want to keep him or his replacement), Cizikas and so on. Minnesota will have only around $14 million in space.
Hopefully Snow has at least one more "bad" deal left in him so the Canucks can take advantage.
regards,
G.