(Maybe an unpopular opinion)
I'd rather not. The EU has already experienced growing fatigue. The further away the member states are, the less they have in common and the harder it will be to agree on political topics.
People in Canada have little in common with europeans, compared to countries within the EU, which are much more alike to another. Canadians are politically, economically and stragegically much closer aligned with the US than with the EU. E.g. a Canadian does not need to care as much about the Russian threat as Poles or Fins do.
I'd love for Canada and the EU to become closer allies but I wouldn't want them as a (current day type) member. The same goes for Australia, New Zealand or Japan. I'd love them as allies but not as EU Members.
A new Type of EU Membership though, which would profit from the single market, the euro, etc. but does not have voting power on people that actually live in europe though, I'd like.
Thoughts and counter arguments welcome
I'm not sure what your post is really about and what exactly a possible future you imagine has to do with an EU membership today.
Also the Russia Argument was just one example I gave. There's so much more to EU membership than just the Fear of a Russian threat. There's economic systems, socialism, geography, culture, standardized systems, city structure, etc. For all these, Canada aligns closer to the US than to the EU.
The european settlers, ex-colony argument also holds for the US. Should we then also consider the US as an EU Member?