Even after getting a PPR and CoPR, you aren't considered a permanent resident until you finish your landing process. So if you haven't completed your landing, you can use your old visa to still come back. But after you finish landing, you are a PR of Canada and you no longer can use your old visas as they are cancelled.Thank you!
So i am on a work permit extension, and i dont have a PPR yet. my question was hypothetical. So now that i have explained that, i shouldn't have the issues that you're talking about, right?
Also, lets say you get your PPR just before you leave or when you are away, you can request for time extension from CIC for submitting your passport.