Have you looked into http://www.musl-libc.org/ as a potential replacement for newlibc? It is posix compliant, significantly higher code quality and very active. There is very little assembler, and usually a C fallback for everything. The only downside is that the author is generally leaning towards linux-only, so a fork may be necessary to run it on other OSes. It should be super simple to maintain tho, since everything is modular. The makesystem is make (weee).
And thumbs up for the talk at the IoT meetup.