Xiaomi's Global spokesperson and Director of Product Management, Donovan Sung, has seemingly shared an image of the upcoming Xiaomi Mi MIX 3 handset. You can see the image above this article, and in addition to sharing this image, he also mentioned that the device is coming in October, and that it will sport "the next generation full screen display, with a sliding form factor". This device's design seems to be inspired by the OPPO Find X, at least partially, due to that sliding form factor.
Having said that, Mr. Sung did not specifically say that this is the Mi MIX 3, but considering the time frame of its announcement, and its design, it quite probably is, unless Xiaomi is planning to launch a whole new lineup of devices with a sliding form factor, which is not that likely. In any case, this image reveals quite a bit of info, actually. First and foremost, bezels on this phone are extremely thin, top and bottom bezels are the thickest, and they're almost non-existent, which says a lot. In an image that Donovan Sung provided, the phone's front-facing sensor are not retracted, and even though we don't know what exactly is located in that panel that slides out of the device, we do see several sensors included on it, along with an earpiece.
That being said, the company will probably include all the sensor on that slide-out panel, as the bezel above the display is almost non-existent. It will be interesting to see if it will be possible to make phone calls without sliding out an earpiece, in other words, did Xiaomi come up with a way to utilize that earpiece even when the phone's slide-out mechanism is retracted. The device will almost certainly sport at least two cameras on the back, and you will be able to use those cameras without utilizing the slide-out mechanism, which can't be said for the phone's front-facing camera, of course. The phone will probably be made out of metal and glass / ceramic, and it will be fueled by the Snapdragon 845 64-bit octa-core SoC. The Mi MIX 3 will sport 6GB / 8GB of RAM, and chances are it will be the highest screen-to-body ratio around, or at least close to what the OPPO Find X has to offer.