If at the beginning of the Egyptian exile, we had tried to predict which of these two tribes would be larger a few generations forward, clearly the mathematical projection would have been that the Tribe of Benyamin would be far more populous than the Tribe of Dan. This statistical likelihood, of course, never materialized.
The Chofetz Chaim (1838-1933) says that we learn from here that if G-d wants to bless a person with many descendents, he WILL be blessed with many descendents, even if through natural factors that is unlikely. "G-d decrees and fulfills His decrees." Conversely, if G-d feels that a person should not merit many descendents, then it will not happen even if he has the best situation "on paper". This lesson applies to everything in life, explained the Chofetz Chaim. It applies to wealth. It applies to finding a suitable marriage partner. It applies to health. It applies to everything!
Sometimes we look at a situation and ask - based on natural projections (derech haTeva) - how will this person earn a living? How will he be able to survive financially? G-d has many messengers. The Tribes of Dan and Benyamin are testimony to the fact that G-d is All Powerful. He has His own calculations. That which we think will happen, by the natural order of events is not always what happens. Everything is in the Hands of Heaven.
The above dvar Torah was adapted from the hashkafa portion of Rabbi Yissocher Frand's Commuter Chavrusah Tapes and transcribed by David Twerskyhttp://www.torah.org/learning/ravfrand/5762/pinchas.html