The beauty of this spec is that it defines a set of basic components to build multilateral federations between various types of entities (without a need to rely on Web PKI + of course, the types of these entities are limited by the imagination only). Regardless of what's going to happen and what isn't going to happen to existing SAML multilateral federations, I think this this specification might begin to be adopted for various other use cases.
It's worth mentioning, the spec was also written by people who aren't new to anything from that, they were already deeply involved in SAML multilateral federations.