Avraham was told hundreds of years before that his children would go into Egypt for 400 years and then they would come out with "great wealth". The entering of the Jewish nation into Egypt was a premeditated affair. The test of Adam after his sin was a test in the reshus, or authority, of the Satan. This meant that Adam had to be omed be'nisayon be'reshuso which is much more difficult than doing shelo be'reshuso. If you're omed be'nesayon be'reshuso, you weaken him and cripple the Satan so that he begins to withdraw out of creation. This is the process of purification. When G-d created the world, He basically constructed two entities, the World to Come and mankind. Before the sin mankind was completely symbolized by Adam; therefore Adam was the one who was supposed to be the sole recipient of the World to Come. Obviously, there was a certain amount of the World to Come created for Adam. Had he withstood the test, he would have merited that amount of the World to Come. After the sin, Adam's soul was fragmented so it was no longer a single soul that merited the World to Come. Instead, the World to Come was also framented in a parallel transformation. With each step of mankind, there is a parallel step in the World to Come because the two are inextricably connected. The World to Come was fragmented in correlation to Adam's soul, so that each part of his soul would receive an equal part in the World to Come.