This is what Scott Hanselman wrote, please read that first:

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I can see why this is initially a scary WTF moment. Let me explain because it’s less freaky than it seems.

You said .NET customers are going to need to interoperate. Totally agree. We can share netstandard libraries between ASP.NET Core 2.0 and EVERYWHERE. We can even reference many net461+ assemblies from ASP.NET Core 2.0 because of typeforwarding and netstandard20 You said WebApps may need to use: AD – Totally, this is a gap IF you want to call LDAP directly. You can certainly auth against Windows Auth NOW. We plan to have specifically the DirectoryServices namespace for Core 2.0 around summer timeframe Drawing – Totally, this is a gap. We plan to have this for Core 2.0 around summer timeframe. Until this, these netstandard options also exist ImageSharp, ImageResizer, Mono options, etc COM Automation – This has never been possible under Core 2.0, but you can certainly PInvoke if you want to hurt yourself. You could also local WebAPI to a net461+ process if you really want to hurt yourself. Sharing code with WFP Apps – YES. Totally possible with netstandard2.0. This is a weird change to make. Feels like it but… Think about it this way. WPF isn’t netstandard2.0, it knows it’s on net461+ and that’s OK. It’s optimized, but it can reference netstandard libs. ASP.NET Core 2.0 is optimize for Core 2.0 but it can reference shared libraries. Xamarin is the same.

.NET Core is side by side and it’s moving fast. It’s WAY faster than .NET (Full) Framework can move which is good. By building ASP.NET Core 2.0 on top of .NET Core 2.0 (which, remember, is a SUPERSET of .NET Standard) that means stuff can be built faster than NetFx or even Netstandard.

NetCore > Net Standard > NetFx when it comes to development speed and innovation.

Point is, if you are doing new work, netstandard20. If you have older net461+ libraries, MOST of those can be referenced under ASP.NET Core 2.0.

ASP.NET Core 1.1 which runs on .NET Framework will be fully supported for a year after we release 2.0. That workload is fully supported thru at least July of 2018.

The remaining large gaps missing in .NET Core 2 are System.DirectoryServices and System.Drawing. We are working to have a Windows compat pack which would enable both of those on .NET Core on Windows this summer.

What we need from you all is a clear list/understanding of WHY you think you need ASP.NET Core 2.0 to run on net461+. Be specific so we can close those gaps and let everyone be successful.