Apple seems to be working on it. A lot of times when I press that POI icon, I get Trip Advisor reviews and not Yelp. Additionally, there is thumbs up/down UI in the Apple Maps app to rate a POI. An example would be Fairhaven Village Inn, Bellingham, WA: no Yelp droppings anywhere to be found.

Given the integration, I'd expect that Apple's decision to build their own would start with buying Yelp if for nothing more than the data Yelp already has.