It will be interesting to see how this ends up playing out. During stage 1, uber was able to win by scaling up driver and rider supply with enough balance to keep everyone happy enough to continue use.
Stage 2, the transition to the self driving vehicle, can be won by whoever is able to supply self driving vehicles at scale.
It is plausible that Google and Apple could create a ride marketplace for vehicle manufacturers. You press a button on your phone and a car shows up. This would provide a survival path for car manufacturers.
Another plausible scenario is cities converting to self driving "platforms" exclusively run by single companies such as Uber or Google. In the shorter term this could be a winning play because it makes the self driving automation part a little easier. Longer term this doesn't scale so well. However, if a larger company is able to get big cities to sell transportation rights there could be long term lock in. There will be big opportunities here in the next 5 years as municipalities continue to become more strapped for cash.
Google, Apple, Uber, Tesla, and BMW are the companies I'm watching closest right now. The big question may be what was more important -- have the rider/driver network first, actually manufacturing self driving electric vehicles (electric is important because emissions and air quality will win cities), or having the platform users use to hail vehicles (Apple and Google.) Uber could have a big IPO and buy a car manufacturer outright but I don't know if that makes much sense. Buying up assets of a bankrupt or bleeding car manufacturer seems more opportune.