Thanks to all of the hard work of the energy extraction industry, future generations will never have to deal with the lack of a Northwest Passage. They will, however, have to deal with a coral shortage.
However, when Roald Admunsden crossed for the first time the North West passage a few years after the Franklin expedition was lost, it was not by boat, but with sleds...
From my understanding, given the size of the Terror and Erebus, the Franklin expedition could not have crossed the NW passage anyway at that time.