How many users will the ISP require before they'll come and patch you into their network?
He suggested contacting the major ISPs here in France to see what their magic number (X) is. I think he's right. So much of the project will depend on whether they can make a business case for selling to 50 homes.
However, I've decided I'm going to put in the conduit/network whether or not we can find an operator who will build out to us and offer services over the fiber. My reasoning for this ties back to the overall goal of the the project. I consider this first and foremost a learning exercise and figure I'll learn either way. Second, I know that even if we can't get an operator to build out to us now they may change their minds down the road - particularly when faced with the prospect of digging up the roads to put their own infrastructure. That will save us trouble in the long run.
If we can't find someone to come in then I can also look into getting a 50-100 Mbps connection into the residence to share.
Hopefully operators would be willing to take a chance on the project because there are ways to improve the scale economies if we can show this works.