OK, revise the question - if the connection to the rest of the world was spotty, say, once a week, instead of non-existent, how would that change things?
My reason for asking this is I am developing a product for deployment in the Third World that Bitcoin is a great fit for, but it must be able to function with only intermittent access to the blockchain and support 50-100 users.
The local Bitcoin network could transfer between local users just fine with intermittent and spotty Internet access, but mining locally would not only be futile, it could even be counterproductive if the locally 'mined' block rewards were to start circulating and intermixing with the existing coins. This would literally take months at the hashrate locals would be able to maintain, and likely be reset every time that the Internet connection was reestablished for any significant period of time, but mining should not be attempted in this scenario, even if it made economic sense. A regular modem call, even an international one lasting hours, would be cheaper and less resource intensive than mining locally; and be much more productive towards the goal of facilitating local transactions. The bandwidth requirements to maintain an isolated section of the network, so long as it is not trying to mine, does not scale with the number of local nodes or transactions. Also, bitcoin doesn't really need a
live connection, if the goal is simply to keep the local network's blockchain as up to date as possible. The occasional snail-mailed USB drive has more than enough bandwidth, and bitcoin doesn't mind the high latency.
