Update: GambitAnimating has put together leaked meshes to showcase what Leaky Lake will actually look like after the Fortnitemares finale event this Sunday. They have low textures due to it being a mesh.
Leaked files from dataminers are showing what is going to be happening to Kevin the Cube over time prior to the Fortnitemares finale event.
The second stage just happened before writing this article, with the Cube combusting and showing very visible damage after dropping a huge chunk into the Leaky Lake sinkhole.
However, there will be 3 fragments of the Cube left according to textures found inside the game files. These fragments may be dropped into the Leaky Lake sinkhole throughout the Cube's wear and tear - or it may be what is left of the Cube once it explodes.
It is expected that Kevin will explode during the Fortnitemares finale event this Sunday at 1pm ET, but we do not know yet. Sounds of the event, codenamed "Butterfly" have leaked.
This is the current state of the cube, which is named as "Weakened".
One fragment has fallen into Leaky Lake's sinkhole, but it seems that two more are expected to be broken off of the Cube by the time the Fortnitemares finale event occurs.
We'll have to see what happens between now and the actual event come this Sunday. We have a countdown to when the event will occur on our homepage at fnbr.co.