> Emacs is an attempt to preserve and further develop the legacy of the lisp machine
I don't think that is true, given that GNU Emacs either was based on principles of general Lisp implementations and it violated / did not support much of the MIT Lisp Machine (GNU Emacs: it's not a computer, the Lisp power was weakened, low-level Lisp was replaced with C, weak GUI, not GUI-first, it's not an operating system, ...) ideas.
> A spiritual successor to Emacs will not be a text editor, it will be a software environment that continues and further develops the principles the lisp machine operating systems were build on
I would think the first part ('software environment') is a useful goal, but the second part ('principles the lisp machine operating systems were build on') is not useful, since the Lisp Machine operating system is very foreign to modern users and very different what people know how to develop and use. That idea is also not supported by the user community. It would lead into a very small niche.