If the GMaps ride service functionality is accessible to other services (it currently is by specific negotiation/partnership only, apparently, so not really, but as a platform that could change), it provides an avenue for weakening Uber's moat and making it easier for competitors to gain traction.
In my city in Spain Uber is not available but GMaps offers rides with Cabify instead, a local alternative. But I think it is negotiated on a case-by-case basis.
