Of course there will be scripting components in the future. We are working on a big update to C#/Python/VB scripting in general in Rhino 8 Rhino 8 Feature: ScriptEditor (CPython, CSharp). There will first be some new scripting components that should show up in GH1 “soon-ish” that work with Rhino’s new scripting framework. Once the updated scripting components for GH1 get polished we can invest time into adding these to GH2.
As this is the initial release of GH2 alpha there is no official SDK. Code is currently changing way too much and way to often to be able to provide any sort of SDK for 3rd party component development. The overall process of compiling custom components will be similar, but as this is a completely different library than GH1 there are obviously going to be differences.