It would slow CA Absolute Ritual pretty down. They wouldn't be able to use the monsters in the graveyard for ritual anymore and I think dakini wouldn't be able to bring others back since they are zombie then?
Bastian would be amazing with this skill. But if Konami gives this skill to either Weevil or Odion it will be seriously busted. Odion has mystical beast serket,and temple of kings: if you tribute summon serket instead of special summoning it,you can use zombie world protect it instead of temple of kings (which would destroy itself without it) however that's why you use zombie world first.
Dakini is still able to bring back Ritual Monsters from the Graveyard to hand, zombie-type change does not affect this. BUT, zombie world player can use Il Blud to SS not only your Dakini, but literally all your monsters from your Graveyard to their field, whichever they see fit.