EDIT: The other thing is that you can theoretically install solar panels or a freaking pebble-bed reactor in them, so when fuel gets too expensive for regular air shipment of crap, this will be the fastest option. Assuming we don't figure out the whole "nuclear ramjet" thing in such a way that it doesn't poison whatever it overflies.
The nuclear ramjet thing is relatively easy, you use a closed cycle (think PWR with the "secondary" loop being the whole atmosphere...). That does impose a weight penalty, though, not ideal.