alt Hacker NewsThere is this Venn diagram[1]. Canada could shift into the Council of Europe like Georgia or join Schengen with an independent currency like the Swiss. The latter would be a nice arrangement for Canadian passport holders.
[1] https://www.reddit.com/r/europe/comments/1qbq43v/european_in...
Canada doesn't share a land border with any Schengen countries, so I'm not sure how valuable passport-free travel would be - you're already taking a transatlantic flight, it's not like passport control is a huge additional hassle.
However, I could see a big argument for a labour mobility agreement similar to the NAFTA model, where EU citizens in a long list of professions have the right to work in Canada and vice-versa.