Hello. Thanks to a friendly help, I've found a few mails and
articles which deserve to be read:

     Udev on non-systemd is a dead-end:
https://lists.freedesktop.org/archives/systemd-devel/2012-August/006066.html

     To face issues with Udev, the Linux kernel team has started 
implementing firmware loading by the kernel itself, by 2012:
http://lwn.net/Articles/518942/

     They also consider loading the modules directly, in  both cases 
ressorting to a hotplugger only in case of failure:
http://marc.info/?l=linux-kernel&m=134921751125528&w=4

     Didier