During this year's Snapdragon Technology Summit, Qualcomm unveiled its latest flagship chipset for smartphones, something it typically does on the first day of the event. Following up on the announcement, Xiaomi's Bin Lin came on stage to announce the first smartphone to be powered by the new chipset, the Xiaomi Mi 10.
This kind of announcement isn't uncommon. you may remember that last year, it was OnePlus who got on stage to announce that it would be adopting the Snapdragon 855 in its next phone. This doesn't mean that the Xiaomi Mi 10 will be the first phone powered by the new chipset to hit the market.
This year's Mi 9 was announced just a few days before Mobile World Congress in Barcelona, so we should expect to happen at around the same time. Of course, by that time, many other OEMs will be announcing smartphones with the new chipset, including OPPO, who also announced on stage it will release a device with the Snapdragon 865 in early 2020.
In addition to a new flagship, Xiaomi also announced that it will be launching the Redmi K30 series next week, and that it'll be powered by the Snapdragon 765 mobile platform. OPPO and HMD Global (Nokia), have also announced upcoming phones with this new chipset - the OPPO Reno3 Pro for the former, and an unnamed device for the latter.
Update: The article has been updated to mention upcoming devices by OPPO and HMD Global.