I have 4 subnets on my LAN interface, so I am unfortanly not able to use
m0n0wall in our production enviroment (m0n0wall firewall rules management
etc.). Are there any upcoming plans to implement this feature, so it is
possible to have more than one subnet on the LAN interface?

I am even though using m0n0wall on my private home network and there it
works just great, thanks! :-)