It can split easily 4.3billion times technically anyway. I think the notion we create smaller currency units as the network grows makes sense. Whether its limited to code upgrades or automatically happens we are not sure yet. Initially it will be code changes but as with everything my goal is to make this automatic requiring no code changes.
If they were all created on day 1 it would be a large management burden on the network so there is plenty of time to see how we as a community want to do this sub-division. It will be better when the whole tech team is focussed on this part alone and not as now with us all working on different parts.
Plenty of options 