It won't affect anyone who shipped their vehicles, they only flew to get around the land crossing restrictions. They will be allowed to drive back, unless the rules morph yet again. This newest development is probably 3 months late. The real question is when the ruling elite will get their heads wrapped around the rules they're implementing.
https://www.cbc.ca/amp/1.5856551
While hiding behind fake Twitter posts, to appear at home: https://amp.theguardian.com/world/2020/dec/30/canada-finance-minister-caribbean-vacation-covid-travel-warnings
Alberta doesn't want Ontario to feel left out: https://www.cbc.ca/amp/1.5859031