I don't see the ability to add a .resx file in Visual Studio 2015 RC. Is this technique changing to something else in the future or is it just missing till the final release on the 21st?
Resx is not going away. We still have them and it works. Here's one from the ASP.NET codebase https://github.com/aspnet/Configuration/blob/dev/src/Microsoft.Framework.Configuration.CommandLine/Resources.resx
The localization story is coming in beta7.