Yes, The Sons of Orion is planned as a central feature to the PU, and revolves around a group of survivors of the Vanduul annexation of Orion. It will involve a series of missions that grow more and more complex and difficult, that primarily involve fighting/thwarting/killing the Vanduul in and around the Orion system. Note that Vanduul swarm was designed as a mere placeholder, and that if your interest is primarily in killing Vanduul, and effecting the fate of the galaxy, you'll want to play SOO missions. If this is your main interest, it was recommended you'll want to play through SQ42 first and perhaps even pick up an F8.