Come on: Newfoundland could have easily remained a colony, and could have easily gained independence a few years later. All sorts of countries were born in the latter twentieth century, economically viable or not.
Newfoundland was mostly in dire straits, yes, because of the First World War - when all sorts of potential leaders were picked off by Germans. Perhaps doing better in that could have allowed them to, at least, survive the Great Depression. World War II could kickstart the economy - not by too much, obviously, like other countries, but enough to give them a boost, and enough to keep them viable, if poor.