Imagine suddenly a new taxi business was able to come into your city and provided taxi rides for 5 cents on the dollar. What would happen?

Edit: now add on top of that that even if uber tried to undercut them again by running losses as they did in the past, that new taxi business would not loose any money if the number of their rides went down because their operating costs simply scale with the number of rides - while uber was loosing money on every ride.