A Reuters article provides additional information on the post-split structure.
Quote of note: “Weiss cautioned that details of the breakup plan were still being discussed and that timing was unknown. But if the plan plays out, he said, ‘the present Milberg Weiss will continue as an entity. Another firm will be formed by Mr. Lerach.'”
Addition: A story in The Recorder confirms that Milberg Weiss is likely to split into East Coast and West Coast operations, with the firm’s San Diego and San Francisco offices forming a separate entity. The article also speculates on the reasons behind the split.