I think you're overvaluing Uber's footing in the current London market. During the summer several competitors have been granted licenses, and they are reporting

I think you're overvaluing Uber's footing in the current London market. During the summer several competitors have been granted licenses, and they are reporting healthy and fast growth. Those millions of people can just switch over to one of the other apps and get a nearly identical (and usually cheaper) service. Same with the drivers, the competitors are offering a hugely better deal than Uber is.