User blog comment:WarpSpawn/(DAT): 20 Primarchs, 18 Legions?/@comment-3258762-20111025153238/@comment-1932673-20111025171102

Well thats the impression GW gave, but its not confirmed, however it is beyond doubt that 20 legions were created and that all 20 primarchs were found, what happens afterwards is a complete mystery.