That's definitely true, question is for how much longer it'll be making money.
WoW peaked at ~12 million players back in WotLK and then has been pretty steadily losing players over the past 11 years. At the end of MoP we were down to 7.5 million players.
in Warlords of Draenor we dipped down to ~5 million players, and Blizzard decided to stop doing subscription announcements around that time.
Given that WoW lost 7 million players between 2011-2015, I'd imagine we're quite a bit lower than those 5 million over these past 7 years, even if we assume that the decline stopped being as sharp as it was before.
Blizzard's definitely focused less on WoW past couple of years so they've probably found ways to cut corners and cheap out to keep it profitable for longer, but we can't be all *that* far away from the line that crosses into unprofitable. WoW has a fraction of the playerbase it once had.