This will not happen, I assure you.
Now I will explain why.
I always consider album Meteora as the 2nd part of the album Hybrid Theory. Not one so I thought. and then was release the album MTM. and on the eve of release of the 4th studio album, I thought it's will be something special, something unreal. But in the end we got 2nd part MTM. Yeah I consider the album ATS it's the 2nd part of the album MTM. I think many people will agree with me. because sounding on these two albums (MTM & ATS) are very similar. for example songs like :
Shadow of the day - Iridescent
Given up - Blackout (The most hard songs in their albums)
Bleed it out - Waiting for the end ( these songs are similar in nature)
- I do not think that the 5th album it's will be the 2nd part ATS ( in this case 3rd part MTM )
Likely 5th album it's will be not the conceptual album, and just collection of songs. Maybe it's will be the album on subject "Life after the end of the world" and on the album will be heavy songs, or something else.