Pretty much, if a third party patch is provided which is fully GPL complient, it will be considered for use. I myself dont know what the grounds for patch acceptance are as far as this goes.
I've had a sort of interest in implementing hexen format maps (compatibility, yay :D) and the ACS VM, but having hardly ever played heretic, hexen, or strife, I'd have no devotion to recreating and playtesting these games.