I'm guessing you're talking about WFTO so I'm moving this topic across there.
Currently the focus is getting the game finished and up to the great quality the Devs expect from themselves, in the future it is possible that there may be paid DLC but it'll always be something big that really adds to the game like new campaigns or game modes stuff that takes that little extra investment of time and money.
There will of course be plenty of free updates and Subterranean Games plans to keep supporting WFTO for a long time to come.
DLC's usually cost money. However, they don't cost much so price is not a problem in this case. What matters however is if those DLCs will be worth their price, nobody wants to pay money for something like a new map and one new skin.
IMO a DLC should be big enough to be worth the price but small enough to make it an option, some games have DLC's that adds so many stuff it pretty much forces players to buy it because without it the mods don't run.