OriginOS 4 will remain an AOSP product, and the first phones to ship with it should be the iQOO 12 series and the X100 flagships. An update roadmaps for existing phones will hopefully be shared at the announcement event.
The in-house OS will be used for connected devices, but is highly unlikely to make it to phones.
Source (in Chinese) | Via
vivo announced it will host its annual VDC (Vivo Developer Conference) on November 1 at the Exhibition Center in Shenzhen, China. During the event, there will be three key innovative software products – self-developed AI for mobile platforms, the new in-house operating system for IoT devices and the latest OriginOS 4 for vivo smartphones.