There is still the problem that without the competition that Uber provides, Lyft likely becomes a more typical company and begins increasing their margins in ways that customers and employees dislike.
Exceptionally low rates means the cars that are picking people up are not the quality of cars people want to be riding in, nor the quality of drivers they want to be riding with.
Uber is still the big dog in town, I doubt they'll disappear completely.
Also, if you listen to the Lyft founder talk about the company, he sounds like he actually wants to help the world. Not to say that they can't become a shitty corporation, but it seems less likely.
Lyft's valuation is still 1/10th of Uber's. I don't think we need to worry too much about Uber going under anytime in the near future. Uber still has another 10B in the bank. As a consumer, I am supporting Lyft so that they might live another day to keep the competition going