do you think that we can add plist support in the future?
In theory yes, but I don't think it's worth the additional complexity. Plists are not a general-purpose data structure; they are mostly used in a specialized way, e.g. for keyword arguments or symbol properties. Supporting alists make sense, they are easy to work with due to let-alist and other alist-specific functionality. But that's not the case for plists.
Or do you have a specific use case where plist support would provide a significant advantage?