Late last year WhatsApp added the option to force your messages to disappear, a la Telegram. At the time the only setting was for the messages to vanish after 7 days, but according to a leak uncovered by some fanatical fans of the platform, that choice will soon be expanding. An upcoming version of the feature with an additional 24-hour option was spotted in development.
WABetaInfo, a reliable source for all things WhatsApp, shows the choice in the iOS version of the app. While this has apparently been in the works for over a month, the screenshot was the first visual indication that it's on the way. The info indicates that the more rapid disappearing option will be available on all WhatsApp platforms, including Android. The 7-day choice will remain an option, though it isn't known whether the new setting will be available for group moderators.
Exactly when the 24-hour disappearing option will show up wasn't revealed. But if it's showing up in a working UI, I'd estimate it's no more than a couple of months away from landing in a beta build. Assuming, of course, that it makes it out of the testing phase.