We're listening and we assure you nothing is changing with your feed right now. We promise to let you know when changes roll out broadly.
— Instagram (@instagram) March 28, 2016
Should there be a change in effect, the user’s timeline will no longer be arranged in chronological order, but rather, content that is shown will be determined through the order of importance to the subscriber. As to who or what will determine the importance level, that would depend on an algorithm.
In other words, individual Instagram subscribers will be able to check out the messages that is touted to be most important to them, appear on the top of one’s timeline. This might also result in the user missing out on messages that one would not if it were to be presented in a chronological order. It looks like Instagram had started to test out the new algorithm already, sending the affected users into panic, but Instagram has reassured them as you can see in the tweet above that nothing is changing at the moment…yet.