Ethereum is a decentralized network so nobody has the last word on what is "official". Vitalik may propose something and everyone may ignore it. The closest thing Ethereum has to an "official" organization is the Ethereum Foundation, but AFAIK it doesn't make technical decisions, and it isn't in control of the software people run so even if it did people could ignore it.
However, Vitalik is very influential, and also very closely involved with the other people working on Ethereum 2.0. So in practice you can take what he announces at DevCon to be the current direction of Ethereum development.
The Ethereum 2.0 roadmap is still changing quite fast, but the following page is a well-maintained summary of the current direction: