You want the Maritimes to have a large and competitive high value-added manufacturing base that doesn't rely on government subsidies to survive?
Grow the population to 10 million, quadruple the capacity of the Ports of Halifax and St. John as well as the cargo capacity of the international airports, improve the road and rail links to the US to allow more volume of goods to be moved, secure cheap electrical supply to feed the base, etc.
Like it or not density and proximity do matter in economies of scale. There is a reason that the Canadian automotive sector is centered on the Toronto-Windsor corridor...Detroit. That's the center of gravity of the North American market. You're not going to have a car plant in Fredericton or Saskatoon because it doesn't make any sense economically (unless you want to heavily subsidize them...forever).
That doesn't mean that the less populous regions and those that are further away from the large US centers can't support some regional manufacturing or become "Centers of Excellence" for specific industries that make sense for their region, but unless you totally want to scrap the concept of global trade (and all the advantages that brings) then you have to focus on where you can legitimately be competitive.
All that being said, I 100% agree that we should focus on moving up the value chain from raw resource exporting. Keep in mind though that as a small country (population-wise) we have to target these items for the export market because domestic demand in many cases won't be sufficient to support the required levels of production to be efficient and competitive. Also, there are already existing suppliers and supply chains in these markets that we'd have to replace...so be prepared to subsidize these industries until they are established and become competitive.