Sub factions for each faction. They extend replay value and make skirmish and online matches have a lot more variety in them. Each of the three sides could be split to have three sub factions each, making a total of nine specialized sub factions. An example for a Nod sub faction could be "Subterranean Superiority". With this specialty, all of that sub faction's units would be able to burrow underground for a short period of time. Another example for a GDI sub faction could be "Mech Superiority". All the mech units for this sub faction would be slightly stronger and more powerful than usual and they would have a unique mech that no other GDI sub faction has. I would love to see an Orca fuse together with a Mammoth tank in order to form a brand new mech! This could be the special mech for the GDI "Mech Superiority" sub faction.