Complex sentence: Downloadable content through Xbox Live was planned for the game for early 2008 but has not yet materialized, and it is it presumed as of August 2008 that no such content will be released.
Split into simpler sentences: Downloadable content through Xbox Live was planned for the game for early 2008 but has not yet materialized. It is presumed as of August 2008 that no such content will be released.