There are some changes coming to NuGet in VS2015 RTM, under the name “project.json”.
How should you prepare for this as a NuGet package author? This article explains.
Disclaimer: I'm not on the NuGet team, and this post is my non-authoritative personal opinion. [edit: removed my article, since the NuGet team are keen to explain this themselves in a few days -- can't wait!]