Not having used a SatNav, I don't know how good they are at navigating London's endless, ubiquitous, and inherently unpredictable supply of road works, road closures, diversions, building sites, 4-way temporary traffic lights, ruptured, poorly maintained, Victorian water and gas pipes, broadband and temporary crane works, and demonstrations, protest marches and festivals of all kinds. Increasingly sophisticated technology only makes it more necessary to limit the supply of taxis, and city traffic in general. There is a limit to how cheap taxi travel can become, because the majority must still travel by bus or tube or train. In any case, black cabs will continue to have a time advantage as long as they're allowed to use the bus lanes. Judging by the number of passengers who give me the postcode rather than the address, and try to put their luggage in the boot (trunk), many people use both black cabs and Uber anyhow, and I think there a place for both. But it is true that the number of black cabs is dwindling, no doubt owing to a perceived lack of job security. Ironically, and this is a pure guess, perhaps it will be saved by Uber drivers doing the Knowledge. If you're driving around London all day anyway, why not do it in parallel? It is a potential escape, at least, from being exploited by a scumbag company that will fight tooth and nail in the courts to not give them sick pay and other basic benefits, and then when it finally loses in the Supreme Court, it makes an advert (which I can't find) saying what a nice, caring company it is for treating its drivers like human beings. Sick world.