Maybe but Greg from OP is speculating that what Zoro experienced will have a super important impact to close the conflict in Wano aka the only one left that rapresent a danger is Kaido (Onigashima himself) but I dont see what Zoro can do for that but for the first case yep.
Not only that but it look like that soul are the main part that is getting a lot spot recently with Luffy&Mom,Oden,Zoro hearing the frozen moon song from hiroy and enma reacting.
He is saying that this might be a way to introduce foreshadowing a climactic and emotional conclusion to the conflict in Wano.
What can make a climacting and emotional conclusion with Zoro experencing the reaper? ZKK