What makes you think that this is a reasonable possibility? Do you have any rational reason for your paranoia other than a "what-if" scenario created as an exercise almost a century ago?
What insight do you actually have into US policy here, other than a sense that you think they're up to something?
I think that as the Northwest Passage opens up, we're going to see disputes -
diplomatic disputes - about things like where the limit of Canada's territorial waters should be, but this will be between Canada and many countries, probably including the UK, not just the US.
If actually relevant history is any indication, this might lead to a trade or diplomatic "crisis" on the scale of something like
the softwood lumber dispute, but not actual armed conflict. It gives me reason for concern, but not concern of invasion.
AFAIK, the only country trying to make territorial claims in Canada is Denmark:
Hans Island - Wikipedia, the free encyclopedia
It's also what people think just before a promised land grab fails to materialize.