Google just announced in their product support forum
[productforums.google.com] that they will retire the stand alone Google Map Maker product in March 2017.
Today, we want to let you know that Google Map Maker features will officially graduate and be integrated directly into Google Maps in March 2017 when we’ll retire the standalone Map Maker product.
Although they call it graduation from Map Maker to Maps, only some parts of the functionality of Map Maker are currently available in Maps and it is to be seen how much of the core functionality will be transferred in the coming months. Since the start of Map Maker in 2008, Google had the habit of removing rather than adding functionality, including removing support for 150 of the 200 countries after the Android on Apple pee incident, and removing support for adding buildings, landscape features and water features.