I just looked up the trade and the 2nd round pick is for this year. So, the Lightning being eliminated last night improves that pick for the Preds. It'll probably be around pick #52 when it could've been as low as #64 if the Lightning had won the Cup.
Also, Stamkos is a UFA and may not be returning, which could mean that the Lightning won't be as good next year, the year that their 1st rounder goes to the Preds (assuming that the Lightning aren't so bad that the pick becomes protected).
So, that trade is looking even better for the Preds than it did a year ago.