...Which is why I prefer to think that by the 2050s, the cities we saw had lost their "major city" status, as others sped past and far ahead of them.
Estimates seem to point to a global population of 9 billion by 2050
Interestingly, the fact that there are 9 billion people on Earth in ST:FC is made to sound as if this were unusual - even before we learn that these people are Borg Drones. But we don't learn whether the true count as of the 2370s should be higher or lower than that, much less what the situation would have been back in 2063.
Would the Borg seek to increase the population from the supposed assimilation date of 2063, or lower it, or stabilize it (considering that the Drones are more or less immortal and normally don't breed)?
Another interesting aspect from the new movies is the presence of densely packed nightmare cities and vast arcologies, where the corresponding original timeline had a sparsely populated San Francisco and, in TMP, one even less urbanized than today. Might the implication be that future population control methods allow for vast variation within a generation? Politics, fashion or religion would be the driving force; cloning, immigration and emigration the primary means (although various ways for removing people might exist in addition to emigration - say, putting them in stasis in wait for a happier future, or sending them to the past, or whatever).
Perhaps after the divergence in 2233, people became more wary of leaving Earth and hence the population boomed? Or immigration skyrocketed, or fifteen-child families became fashionable all of a sudden. Or perhaps people just chose urban lives over rural ones, and the total population in both timelines is more or less the same.
Timo Saloniemi