"We are going to emulate all computers and physics even when players aren't logged in."

I built a prototype trying to do something similar, inspired by a text-based RTS/MMO that kept running while you were asleep. For me this was an unrealistic goal, if the simulations are complex enough you can't operate at a price point users will pay for. Even if you can, because the game is now CPU bound, far less players fit on a single instance -- you now need incredibly clever partitioning and load distributing facilities to keep the world appearing seamless. Even AAA titles haven't solved that problem, a look at world PVP lag in EVE or WoW will tell you as much.