In a previous blog post they basically said they will never make a Go 2, and also addressed a lot of things about compatibility:
In particular they said:
> The end of the document warns, “[It] is impossible to guarantee that no future change will break any program.” Then it lays out a number of reasons why programs might still break.
> For example, it makes sense that if your program depends on a buggy behavior and we fix the bug, your program will break. But we try very hard to break as little as possible and keep Go boring.