Some people speculate the DLC will be splitting an Umbrella Civilization like DoI. I think the best candidate for splitting is the Malays. Currently it is being used to represent all Austronesian Indonesian groups.
They can be split this civ into at the very least into 4 distinct civs:
The Visayans (representing Philipines and Polynesians), The Chams (representing Austronesians of Indochina), The Javanese (representing Bali, Java, Sunda, Borneo, Molucca), The Malays (Representing Brunei, Malacca, Sumatra)
It is a very large umbrella as of now encompassing a wide range of people.
Though I would prefer if it comes with a new architecture set inspired with Batak Style.