What concerns me most is how Facebook may use Parse as a way to consolidate their place in the mobile app space. Just as they've done in the past with their SDK

What concerns me most is how Facebook may use Parse as a way to consolidate their place in the mobile app space. Just as they've done in the past with their SDK, what if Facebook decides to block access to apps that compete with for example, their messenger, Instagram etc? Also, who owns the data?