Linux is fine, it's just a kernel. Innovation goes into the user space, between /sbin/init and /bin/sh. I, for one, would start changing all the configuration files of /etc/ to a standard format: json, yaml, scheme, lua, python, it doesn't really matter, just abstract that part away.
The underlying API is always going to be POSIX and the ABI is going to be C based which in this age we can do better.
Regarding abstraction - there is way too much already.
A platform should stand alone and self host be viable, which is impossible with the Linux kernel as you have to pull in most of GNU to build it and change it.
