Geography is, so to speak, the stage on which life acts, directly shaping the fortunes of species and clades. For any project in speculative biology, the geography of a world needs to be carefully considered, and so does the way it changes in time (planets conductive to life will most probably have tectonic activity to change the position and nature of continents). A particular case occurs in future evolution, as the geography of Earth in the next millions of years directly follows from what it's like now; to a certain measure, it's possible to predict it.