You can still post to Instagram without sharing the photo on Facebook. So this "paranoia" - if I may call it that - is only because Facebook now has acces to all of Instagrams information? And Facebook will abuse this position why, exactly?
The current trend with buyouts seems to be eventual integration. Google recently did this with their privacy policy, and it was received with mixed feelings. I see no reason to expect Facebook's acquisition of Instagram not to change how the latter operates: it must become profitable to FB somehow (beyond talent), and data is the most straightforward way. The two blog posts announcing the acquisition aren't legally binding with respect to the future of the products, and nobody should be surprised if a 180º shift happens in a few months. Facebook is in the business of monetizing user data after all.
Exactly. Imagine one day just browsing Facebook casually and enjoying the free services they provide when all of sudden you see an ad on the side that is about an ukulele star throwing a little concert in your home town. Except, you only ever mentioned learning ukulele on Instagram!
