I'd say the relationship between Wikipedia and Google is symbiotic, at least for now. They collaborated on merging the Wikidata dataset and Google's Knowledge G

I'd say the relationship between Wikipedia and Google is symbiotic, at least for now. They collaborated on merging the Wikidata dataset and Google's Knowledge Graph, so now the entities can be connected. Google gets the benefit of their dataset for their knowledge boxes. You can see the difference in the source code of searches looking at the entity ids, /g/ is Google's own data and /w/ is wikidata sourced. I see the relationship Google has with Wikipedia similar to the one it had with DMOZ. I imagine at some point in the future that Google will see them as surplus to requirements, though not quite sure how they replace 5 million volunteer editors economically.