For the environment? Very unlikely to happen, at id all artists had the entire dataset available online at any time and multiple users were able to edit the same area concurrently.
This would be impossible to do over an internet connection, so the only thing contractors could help would be characters and dynamic objects like weapons, vehicles etc. All of which were already done with outsourcing on Rage already.
The game world itself, where the magic really happens with all the manually painted details, has to be done on site. One part, increasing world texel density, is indeed just a hardware related problem and can be solved with larger online storage at the studio and faster network and a bigger disc to ship on; but the other, a larger and more interactive world, would require a much bigger team to complete.