I was thinking the same... although with a little less doom & gloom. One of the reasons ZipCar, et al. have been successful is they exist in places where owning a car is impractical (infrequent use vs. price tag, upkeep & parking fees) so short term, ad hoc rental is optimal. If you remove the costs (since bikes can be pretty cheap, low maintenance and easy to store in your domicile) infrequent use does not make bike ownership nearly as impractical as car ownership. I could see moderate success in a tourist market. I could see jumping on BART into SF and renting a bike to ride around for the day. Those services exist but not in a "self serve" capacity like ViaCycle.