Ask HN: Relying on Instagram's API

HN,

I'm building a website that revolves around advertising on Instagram. It relies heavily on their API for sign up and creation of user profiles. It does not violate their Terms of Use. I've been building an MVP. I'm concerned that they may cut off API access of it gains traction post launch. Does anybody have experience with a similar situation and care to share how it played out? Also, is it worth trying to talk to someone at Instagram before hand?

PS. I think I've seen Mike Krieger comment on HN before, would love to hear his thoughts if anybody would be willing to forward this link to him.