Technology and IPs will be shared between the two popular renderers. According to the announcement this has already started to happen, revealing that V-Ray's DMC sampler is responsible for the 2x speed increases seen in Corona 1.6 hotfix 2. Short-term plans also include the inclusion of VFX features in Corona 1.7 which were co-developed with Chaos Group, and compatibility between assets so that materials, proxies, lights etc. will work in either engine.
You can see the announcement in a recording of the D2 livestream on Facebook and read more on Render Legion's blog and Chaos Group's website.