Assuming that authoritative sites, at least, don't abuse these schemas, this will help all search engines and data mining/nlp researchers build better models. The biggest gain isn't quick view of search results, it's that now search results will be better in general because Google et al will now understand if a page is really about a person and in many cases, who specifically it is about to point out a specific example.

Information extraction, just got that much easier. Hello, baby semantic web.