Based on the recent chapters and context clues we have in the story, the One Piece itself is probably the key to changing the world somehow. However, there are clear implications that suggest that the treasure falling onto the wrong hands may be catastrophic.

If Joy Boy knew this, I think he would put in place measures to make sure only the correct person could do it and that correct person is the person who is capable of awakening the Nika fruit.

I believe that the Roger Pirates were able to go to Laugh Tale and learn the truth. They learned about what they need to do, but they weren’t able to access to utilize whatever the treasure is because if they could, I don’t understand why they would not.

I think there are several things that hint to this being the case.

1. No one has been able to awaken the Nika fruit since Joy Boy.
2. No one has accessed the One Piece for 800 years.
3. Shanks went after the Nika fruit and spent time in the East Blue, potentially looking for Ace or someone who might be able to awaken it.
4. The Celestial Dragons don’t seek the One Piece. Maybe because Imu already is aware that no one could actually get to it.
5. Shanks waited for Luffy before beginning his search for the One Piece. Maybe he was already aware that using it is impossible without having someone who has awakened the fruit there with it.
6. The actions of the Roger Pirates. The Roger Pirates as a crew were strong enough and/or could gather allies such as Whitebeard and Oden and do what must be done with the One Piece after learning the truth. Maybe they simply couldn’t because Joy Boy hid the treasure behind the requirement of awakening the Nika fruit. Because the person who awakens it would have will inline with the fruit and they would therefore be good at heart. That would allow Joy Boy to trust that individual with the One Piece.