(Cue Dr. Evil voice)
...for one billion dollars.
From the blog post from the Instagram crew:
It’s important to be clear that Instagram is not going away. We’l be working with Facebook to evolve Instagram and build the network. We’ll continue to add new features to the product and find new ways to create a better mobile photos experience.
...at least until we're able to cash our billion dollar cheque. Then we're outta here!