Google Maps may get whole country offline map downloads as part of a future update so they could pull up the map when there's no internet connection available. Though this isn't something that's currently possible, code recently found in the latest version of the Google Maps beta APK seems to be pointing towards the possibility that such a feature is going to be added into the app at some point down the line, when though is unclear and that's assuming that Google does decide to make this functionality possible.
The most recent version of Google Maps is now version 9.55, and aside from hinting at the ability to download maps for offline use for whole countries, Google Maps now includes the notification channels for Android O users. This means that even if you're on this new version of Google Maps, which you can download from the button below if you haven't already received the update over-the-air, you won't have the notification channels options unless you're device is running on the Android O developer preview software, which is of course limited to a select number of devices right now, which also means that the notification channels is limited to that same number of select devices.
For the users that are running on Android O and have updated to the latest version of Google Maps, if you navigate to the notification settings for the application you'll be able to manage the notification options for the various things that Maps would generally send you an alert for, like traffic details, transit information, ride services, people & places, and more. Moving back to the offline maps changes, it's not currently clear how Google is planning to implement things. It's suggested that Google may design the feature to allow users to download just a specific region of a country, or it could be a little bit less granular and just allow the download of whole countries. Whatever the case it seems Google wants to give more access to users in regards to offline maps use. In the scheme of things this is a pretty minor update to Google Maps but any improvements are always a good thing.