Many users expressed their intention to remove Instagram on Twitter
Some tech blogs even post tips and tools to get users' data out of Instagram such as Instaport. Users also find an Instagram notification that allows users to delete accounts. (However, the advice for you is not to rush to do anything unsure, when deleting an Instagram account you won't be able to register again under that name anymore.)
Obviously, users' concerns are not about Facebook changing Instagram or closing this service (this is not possible). Users interested in Facebook are invading privacy and collecting all personal data into large databases.
Will users be overreacting, or perhaps they just want something smaller, more private?
That's why other small and specialized social networks (Path, Pair, Pinwheel .) were born to serve users' needs and replace (or even escape) a Facebook with size and Scary scale.