Of course, momentum is not a static number. Things change, new features get offered, and the analysis done by Dediu assumes that everything stays the same. The analyst adds, "One should be careful about drawing conclusions that this implies effective competition. Both platforms are growing very quickly. iOS is growing at at least 100%/yr and Android’s second year was 65x bigger than its first. iOS growth is limited by the ramp rates of a limited portfolio of products. Android growth is limited by how quickly vendors can bring out products. Neither platform is demand constrained and hence they are competing for share of growth not for share of a fixed pie."
He also says that "extrapolation is a dangerous game." For example, had he done this comparison even just a week prior to the launch of the original Motorola DROID, the results would have looked quite different.
source: asymco via AndroidGuys
According to analyst Horace Dediu of asymco, by next year Android users could number the number of iOS users