... one virus could kill the world?

Maybe you know the game „Plague Inc.”. The aim of the game is a bit brutally. It is to kill the world with one virus. I was questioning myself if it would be possible to kill the world with one virus, or bacteria or what would happen with our planet after the human?
Soon I found out, that it is not possible to kill all the people with one virus. First of all, we have to know, that a virus is something very small

(15 to 500 nanometre), very infectious, but also it can not survive on his own, like a bacteria can, for example. Exactly this is the reason why a virus couldn’t kill all of the people. If a virus would kill every host cell, it would be suicide for this type of virus.
Okay, now we know it is not possible to kill the world with one virus, but let us continue this mind game and crate one special virus, who has the incubation time of Salmonella (a few hours), the infection of Influenza (via the air) and the capacity to mutate like the HI-Virus, but also we need some properties of Bacteria’s, like the capacity to survive without host cell, for example.
Now, with this creature we make the impossible possible and kill everyone in the world. Without the human, the nature would come back and our “green planet” would become green again. Cursed by the natural selection, the monkeys would educate themselves further and end up in thousands of years as kind of human.
In my opinion, it is not possible to have an earth without human, but we have to keep in mind that we are not the only species on the earth and we have to take care of our planet in a good way.