"Stop calling it buying" now that's a good start. Clearly showing the player at the time of buying that the license will expire at EOL is a great way to set expectations properly

As for the exact time the license may expire: that would vary greatly based on the amount of concurrent players and the revenue the game generates, so the best estimate we can really have is whether or not the game generates enough money to continue supporting it (running servers costs money after all)

Overall, clearly setting expectations is the goal that this initiative should have been gunning for, but unfortunately that wouldn't make as much of a sensation in the news