Maybe the plan was to only try to change the past. Maybe it was the point of preparing us for DW. After all, if Nozdormu can see multiple futures, but they all converge on to the Cataclysm. Fail and we have the future we glimpsed in the first HoT dungeon, succeed & the Timekeepers can't see well enough to know if it's better or worse. The not knowing could be what drove him to madness. Either way, I believe we are beyond the reach of the Infinite DF as they are apart of a different future.