A new exclusion has been added to Supreme Commander 2 that gives you the option of excluding DLC units. Gas Powered Games haven't released any DLC, though. At least, not yet.
A steam forumite pounced on a Gas Powered Games poster to ask about the exclusion. Thejuice027 asked, "What is this 'No DLC Units' exclusion? Is it that we have downloadable content units available that I don't know about, or DLC units coming soon?"
The reply was "It's a secret." Ruh roh.
It would make sense to add something new to the SupCom 2 mix since the launch of StarCraft 2. While some of us here are still suffering from plenty Banshee-related insomnia, I've started to tire of the 'Craft and return to my grand bot matches in Supreme Commander 2. We'll be phoning Gas Powered Games to ask the same question hundreds of times in an annoying voice until they tell us what this all means, but know this: it's probably DLC with new units.