As stated here:
There's no word atm if these are for free or not. But if you have to pay for them I just hope they'd take the same direction like End of Nations did knowing that you can download units and factions:Ever-evolving Experience – Enhance your game with an expanding array of downloadable content. From maps and units to factions, campaigns, and more, the fight against terrorism is deeper than ever.
Is End of Nations going to be pay-to-win?
No. Core to the design of any successful strategy game is that all players are on a level playing field. It will not be possible for players to buy their way to success, where the player with the most money will win. End of Nations favors strategy and skill.