Kevin Systrom:

The Instagram app will still be the same one you know and love. You’ll still have all the same people you follow and that follow you. You’ll still be able to share to other social networks. And you’ll still have all the other features that make the app so fun and unique.

Mark Zuckerburg also made an announcement on Facebook:

We think the fact that Instagram is connected to other services beyond Facebook is an important part of the experience. We plan on keeping features like the ability to post to other social networks, the ability to not share your Instagrams on Facebook if you want, and the ability to have followers and follow people separately from your friends on Facebook.

I’m not sure what to make of this. They both make it sound like Instagram won’t be affected at all, but for this to make any sense for Facebook, the Instagram experience will probably have to suffer in some way.