The question that I raised one month ago about support for add-ins in Visual Studio 2013 already has an answer: they will be supported. If you install the Visual Studio 2013 Preview or set a virtual machine in Windows Azure with the Visual Studio 2013 Ultimate preview image (my approach), your will notice two things:
1) The Add-in Manager is still there.
2) In the New Project dialog, the “Other Project Types” “Extensibility” node doesn’t exist (nor the “Visual Studio Add-in” template).
About this second fact, I guess that now I can reveal this: Microsoft consulted me confidentially many months ago about moving the “Visual Studio Add-in” template to the Visual Studio SDK and I thought that it would be a good idea, a more natural place with other Visual Studio Extensibility (VSX) templates. And certainly, if you install the Visual Studio 2013 Preview SDK, the “Other Project Types” “Extensibility” node appears with the “Visual Studio Add-in” template and others for “Visual Studio Package” and “Visual Studio Shell Isolated”. BTW, I requested Microsoft support for add-ins in the Extension Manager (removing Add-in Manager), VSIX, etc. as other extensions (to gain parity) but it seems that to no avail. Add-ins will remain as second- class citizens in the VSX ecosystem.