Locus of control is the degree to which people believe that they have control over the outcome of events in their lives, as opposed to external forces beyond their control (see the Wikipedia entry for more details).
Simply put, the old (centralized and federated models) the locus of control was between the other parties that could make decisions about me, whether I was in the picture or not. In the new model (self-sovereign identity), the user is put into the centre of his/her own locus of control. See above.
For a long time to come, all of these models will co-exist. But until recently, with self-sovereign identity, a new model has emerged that has put power back into the control of the individual. It will take time for the ecosystem to work itself out, but I am hopeful we now have a new dynamic force that is going to shift back into the favour of individuals.