The earth will run out of space before that happens. "If the current [population growth rate] of 1.3% per year could continue, the world population would grow to a density of one person per square meter on the dry land surface of the earth in just 780 years, and the mass of people would equal the mass of the earth in just 2400 years" (http://www.albartlett.org/presentations/arithmetic_populatio..., http://www.youtube.com/watch?v=9znsuCphHUU&list=PL63DAFC...).