I don't think decentralized identities are looking to replace centralized attestation. Instead, it is trying to provide a way for users to be their own identity provider, where they are able to interact with 3rd parties, using their identity, without the need to have another service hold or control their identifying information.
A user using a decentralized identity system would still need to go to centralized authorities, like a government office, to be able to get attestations about who they are. But the shift is that these attestations would exist on an identity in full control of the user (self-sovereign identity). Thus, the user has the full ability to choose who they share that information with, and what information they share.
This is different than existing centralized identity providers where your identity information is duplicated and stored on many different centralized systems. Once they have your data, it is really up to them what happens to it. It is also up to them to protect your data from attackers, and ultimately makes them a huge target for attack since they are now a treasure trove of user data. This again is different than decentralized identity solutions where it would require a separate attack on each individual user in order to compromise that user's identity information.
You can watch a video of uPort's test integration with the city of Zug, where it directly involves the use of a centralized authority to provide an attestation that the user ultimately keeps and gets to use with a self-sovereign identity: Paul Kohlhaas - uPort: Self Sovereign Identity in Zug