This is one of the discussions we had at the Reproducible Builds Summit last week: https://lists.gnu.org/archive/html/guix-devel/2015-12/msg001... .
In GNU Guix, we don't go as far as the author suggests (starting from a FORTH-like VM, then building a small Lisp, etc.), but we've been thinking about going in that direction: We already have Guile Scheme at the bottom, with which we can implement a range of tools, ranging from HTTP/FTP clients to ELF parsers, and more. We could imagine having (possibly feature-limited) variants of some of the bootstrap tools, written in Scheme, for the purpose of building the "real" tools.
Our current bootstrap looks like this: https://www.gnu.org/software/guix/manual/html_node/Bootstrap... .