According to the published roadmap, which may change over time, the next major version 2.1, should be out in the first quarter of 2018. We can probably expect pre-release versions by the end of this year, as usually happens.
There was talk of AppDomains coming back to .NET Core, we will probably see more APIs ported, and maybe we’ll have .NET Standard 2.1, bringing us closer and closer to a “full” .NET framework.