Blizzard Entertainment typically announces World of Warcraft subscriber numbers every three months in its quarterly earnings report, but that's coming to an end. The company has confirmed that this week's announcement of 5.5 million subscribers is the last time the company plans to divulge those numbers.

"Note that this is the last quarter that we plan to provide subscriber numbers," the company said. "There are other metrics that are better indicators of the overall Blizzard business performance."

Instead, Activision Blizzard will use other unspecified "engagement" metrics to talk about the health of WoW. These were not detailed during the earnings call where the announcement was made on November 3.

WoW's 5.5 million subscribers as of September 30 represents a loss of 100,000 subscribers over the past three months. The game's subscriber figures now stand at a nine-year low.

Looking ahead, WoW's next expansion is called Legion and will be on display later this week at BlizzCon. No release date for the expansion has been announced, though a beta will begin later this year.

History shows that WoW subscriber figures increase with the release of a new expansion. So it may not be surprising to learn that Blizzard's new plan for expansions is to release them faster. In order to do this, the game's development team grew in terms of head count, as of October 2014, it's bigger than ever before.

Beyond Legion, Blizzard is already planning multiple more expansions to follow.