In Star Trek VI: The Undiscovered Country, the destruction of
my namesake Praxis causes an ecological disaster on the Klingon homeworld and paves the way for a serious peace effort between the Federation and the Klingon Empire. Spock, addressing the Commander-in-Chief of Starfleet, a collection of admirals, and the senior officers of the Enterprise A, claims:
The Klingon Empire has roughly fifty years of life left.
More specifically, the Federation President makes the following pledge to diplomats at the Khitomer Conference:
The proposed agenda is as follows: the total evacuation of Kronos has been calculated within the fifty Earth year time span. Phase One: preparation for evacuation....
This was in 2293. However, from Next Generation episodes, we see that the Klingon High Command is still based on Qo'noS in the 2360s.
Was Qo'noS actually evacuated? If so, was the evacuation only temporary? If it was never evacuated, then what caused the plan to change?