There are no dis-economies of scale. It is cheaper for EK to have pilots in Dubai compared to Europe of Australia. This is simply because they can get away with lower salaries in Dubai due to no direct taxation. If they had basings the salary would have to increase to a large degree to cover the tax aspect which would largely offset any gains made due to accomodation and education expenses.
There will be no basings due to financial reasons.
There is only two possible reasons. The network becomes so complex that it is dictated by crewing/FTL issues or they cannot attract enough pilots. Neither of these issues are significant at this stage.
V