People relying on features that aren't in .NET Core can keep using full .NET, and that's the intended result. Full .NET is going to be supported for the foreseeable future.

However for those projects that don't need them .NET Core is an interesting alternative especially with cloud deployment to Linux or a BSD host.

I work at a large .NET based company whose core product could not work on Core, but we certainly are considering it for newer projects. I'm also many years past being a junior developer.