Before you can improve something, you need an overview. Prof. Dr. Wolfgang Hommel and I in our paper “An Overview of Limitations and Approaches in Identity Management“, which was published at ACM ARES this year and can additionally be found at arxiv. You can also find brief information on Identity Management Sota Publication.
We examined centralized, federated and user-centered identity management and compared different approaches with created requirements. A second, matching paper, which further develops the identity management models that exist so far, was presented at DETIPS 2020, but has not yet been published.