First of all, if we get the fixed link and Route 138 is not completed, then I don't see any benefit. I think the two go hand in hand.
With Route 138 completed and a fixed link between the island and the mainland, transportation time from central Canada to the island and to the lower north shore of Quebec would be reduced tremendously. Right now, goods shipped from Ontario or farther west have to come through New Brunswick, Nova Scotia, etc. As the mayor of Channel-Port aux Basques indicated, there were a number of crossings cancelled this year, so trucks sit on the other side for days at a time. The impact shows on the shelves in the grocery stores. I have never seen produce and fresh fruit in as bad shape as I've seen it this year, along with bare shelves.
Completing that road connection from central Canada to the Atlantic provinces, in particular, Newfoundland, would reduce the cost and speed up the time.