No way - $40B is just nuts, and I think underestimates the ability of other companies to get in on the action. Many of the drivers I've used have multiple smartphones running, one for each service, and just bounce around to whichever gives them bookings. Add in multiple new services - and Uber's growth will suffer.
Uber is a true disruptor but it can't be worth $40B! It's got massive growth but does it have the ability to keep control? Like mikehawkins I think the market share will dilute. Look at what happened with Meercat and Periscope.