Hi Alexander!
I've checked with VS2017 and you can set up your project file like this to get it to work (it compiles on my system):
<Project Sdk="Microsoft.NET.Sdk">
<PropertyGroup>
<TargetFramework>netstandard1.4</TargetFramework>
<PackageTargetFallback Condition=" '$(TargetFramework)' == 'netstandard1.4' ">portable-net451+win8</PackageTargetFallback>
</PropertyGroup>
<ItemGroup>
<PackageReference Include="Remotion.Linq" Version="2.1.1" />
<PackageReference Include="Remotion.Linq.EagerFetching" Version="2.0.1" />
</ItemGroup>
</Project>
The same does for project.json in VS2015, but with the imports-directive (e.g. in the question
http://stackoverflow.com/questions/40676344/adding-framework-imports-to-csproj)
Yes, you have to do this for every project that references the library with the PCL-dependency, which is obviously a pain and the reason Remotion.Linq itself already has a .NET Standard package. As I said, the native build is on the todo list but I don't have a timeframe when to do it and it's possible to do the VS2015 variant first by porting all the .NET Core commits in Remotion.Linq to Remotion.Linq.EagerFetching (i.e. excluding 2861933c32a57f5676dbb990a13416ccfb18fd03 to including 29cd82725117fd43f3fb6966ba76da719e36111d)
Best regards, Michael