Rainbow Six Siege DLC will be themed by nation
Future Rainbow Six Siege DLC will be themed by nation with USA, Brazil, and Japan to be featured. It hasn't been announced when these will be released.
Rainbow Six Siege's first piece of DLC, Operation Black Ice, featured Canadian operators, and future packs will be themed around other nations.
An Investor Day presentation indicates that the USA, Brazil, and Japan will provide Operators in the future. These packs will be rolled out in Q2, Q3, and Q4 of 2016 respectively.
Each DLC pack is expected to feature two Operators as well as a new map. Players can unlock all of the content using in-game Renown, or can purchase the Season Pass to get instant access.
Ubisoft is yet to confirm when these DLC packs will be released.