The release of memories into the community when Jonas leaves would certainly create change in the sense of causing the residents to feel physical sensations and emotional feelings that have been unknown since they adopted Sameness. It may be that this new experience would cause the residents to find value and worth in differences, leading them to abandon Sameness in spite of the potential for pain.
On the other hand, the community might find ways to suppress the released memories and return to Sameness as soon as possible. The members of the community liked their lifestyle - as The Giver told Jonas, "They don't want change. Life here is so orderly, so predictable-so painless. It's what they've chosen."