.NET Core will welcome this round of Java orphans with open arms.
First it needs to sort out its history of not being compatible with all .NET Framework libraries.
https://visualstudiomagazine.com/articles/2018/10/10/net-key...
The presenters said it will still be released with Windows, as it's a component of Windows itself, so it will be supported for the lifetime of Windows. Microsoft is just going to be making highly compatible targeted improvements to .NET Framework after version 4.
So you shouldn't feel pressured to move off .NET Framework, but just know that it's going to be much more highly targeted compatible fixes kind of going forward and we recommend that all new development that you start on .NET is on .NET Core if possible