Google is always innovating and their most recent exploit is no exception. The company is now putting cameras on sheep to get Google Earth images for some remote islands that it wouldn't be practical to map themselves. This is truly a step forward for Google, as well as the rest of the world. It's helpful for images of places to be on Google Maps in that it makes a more immersive experience. Speaking from personal experience, being able to actually see a location on Google Maps when you are lost is immensely helpful in finding the correct location, much more so than a plain old map. There is no cruelty to animals or any other harm being caused by Google doing this, but the payoff could be immense.
With the advance of technologies such as drone cameras, and the ingenuity of man kind, I am sure that we will find a way to photograph the surface of the earth. Drones have helped us to get aerial shots of the ground without the high cost of taking out a plane or helicopter, which makes it far more financially possible to map the earth with images.
Although, it is impressive the mapping Google has done and I have no doubt will continue in the future. Mapping the entire world seems out of scope for Google. To go to war torn lands, the nearly impossible terrain (amazon gulches and middle eastern caves), and not to mention the ocean floors there is no return on investment and since Google is a business, it will not spend the hundreds of millions of dollars if not billions to map the entire world.
No, I don't think that Google Maps will map everywhere eventually. There are some authoritarian regimes such as North Korea which will never agree to Google maps having access to the country. There are still huge swathes of the world with no Google maps information including Western Europe so I don't think that Google maps will be ubiquitous any time soon.