There are five regional registries, ARIN, APNIC, RIPE, LACNIC and AFRINIC. If these registries decide to dethrone ICANN, they can do that. It wouldn't take long. ICANN is mostly just a glorified maintainer of some small databases which store delegations of namespaces.

The registries could render ICANN powerless on the spot. There is literally nothing ICANN could do if the registries decided to handle ICANN's responsibilities in a newly created organization that they agree upon. Same with the domain registrars and the DNS root server operators. ICANN is only at the center of it all because and as long as it kinda works.