Here is my tentative plan to act on the proposal:
1. We start requiring GNU make in an "experimental" automake 2.0
development line (which might, and will, break whathever
backward-compatibility gets in its way).
2. Concurrently, we continue to support the more portable (and
tested, and used-in-the-real-world) 1.x line, with bugfixes
at least (and probably also with addition of new not-too-big
features).
3. We publicize this move in the automake (1.x) web pages,
documentation, etc, inviting users and developers to try out
the new "automake 2.0 pre-alpha", and to send cricisims,
suggestions, praise and ranting to the automake lists.
4. Time and user responses decide wether automake 2.0 will
succeed or die out.
WDYT?