NO the world is not over populated. It seems to be when you go to areas like London, Los Angeles, New York, New York places like that. If the government would not limit areas of the land, the people could move out a bit from city life and live in the country.
In the 20th century alone, there were more people in the world then the first 19 centuries put together.
War is started for reasons you stated, due to over population of people. War is the fastest way to get rid of thousands of people. Its not right, but thats one reason the world has war.
Nobody can tell you what it will be like in 50 years, you can't predict the future, only God can. In 50 years we all might be in the world walking and talking with Jesus, during His 1000 year reign that is to come. Or in 50 years, the world will be trying to survive from the nuclear fallout (destruction) that was caused by Iran, North Korea, and countries that retaliated against them.
If the world was over populated.. every square inch of the land would have someone living on it. In Canada alone they only have 30 million people. Their land mass is much bigger than the United States. California has six million more people then all the Provinces of Canada put together.
Now if your question would have been limited to city names like I mentioned above, yes it is over populated. You must not have done a lot of road traveling across the United States. You would have seen there are lots of open land from west to east coast and from the Gulf of Mexico to Canadian border.