Uber's revenues were leaked earlier this year(http://techcrunch.com/2013/12/04/leaked-uber-numbers-which-w...), they're earning buckets of money and would thrive without VC investment, assuming they can continue to shirk regulation.

Long term if cities allow services like Uber and Lyft to exist the margins will likely decrease since drivers can switch to the company that pays the best, and consumers will use the service with the best rates.