Definitely agree that big, popular dating sites won't be quick to pick this up. I do see the possibility of them monitoring the usage of the API and perhaps integrating some 3rd party API's into their sites too.
What the dating API allows you to do is show off not only what you SAY you're doing, but what you're ACTUALLY doing. It adds an additional facet to someone's profile, which only enhances online dating in my opinion. Could be something larger players would want to look into.
The ongoing trend of mobile dating and social apps should benefit from this release.