I’ve been playing WoW since beta so it’s safe to say I am well-versed in the game. There is, and has been for some time, a gambling world within World of Warcraft. While casinos are not an actual mechanic of the game, there are player-made gambling and casinos available. Some guilds will do gambling or raffles as part of their dynamic and while Blizzard is a bit vague about whether or not gambling is actually allowed, they tend to ignore anything that might happen within a guild. This is because they consider the joining of a guild to be a voluntary experience not directly connected to the game dynamic itself. So if your guild sets up a casino, they’re not likely to care unless you’re trying to advertise it outside of your guild.
WoW’s rules do state that “Advertising in-game gambling or casinos” is a violation of the rules and falls under ‘spamming’ but it doesn’t specifically state that gambling itself is against the rules. There are some gambling addons that you can also get for WoW. Most of them work by allowing you to choose the amount of gold you want to bet. Then all players participating will roll a number and the wins and losses are based on the highest and lowest numbers that are rolled. There are also /roll games that allow you to have a little silly fun within WoW.
That said, there is not a very high chance that Blizzard will ever do anything official with this partly because of liability issues. You’re not likely to see a live roulette feature like leovegas added to WoW, for example. However, if you really love WoW and you love gambling, there are still ways for you to get your fix of both at the same time.