RCS is in theory and intended to be a carrier service. From what Apple announced, all we know of what they are doing is is 1) adding RCS protocol support to Messages and 2) working with the GSM Association to beef up security, somehow.

In reality, RCS is practically a Google service at this point, and we don’t know a damn thing about how that is going to affect interoperability since the carriers have more or less outsourced the service to Google.