What about the actual building wiring? It doesn't matter whether there's fiber to the building if cable has enough bandwidth to fill the copper between the cable box and the apartments.
It might work, assuming the building can support multiple cable providers (e.g. it's not all just 1 trunk from CableCo), but it would cost more in equipment. You would need to convert the fiber to coax (maybe with an intermediate step of ethernet), and then the customer would need a modem to convert from coax to ethernet. It'd be a pricey installation and continual maintenance of hardware.