In some places (all, IIRC, outside of the US), the Google Maps ride service feature already supports non-Uber ridesharing services. In the US, I think it only has Uber, but its basically a feature that lets GMaps be a platform for commoditizing ride services.
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.
