Emirates would make a nice addition but Virgin? It's not like they'll be adding any new destinations to the Skyteam network, and they don't even have a proper (3-class) First for redemption purposes.
ST should think out of the box and approach "unconventional" partners like ET in Africa and TAM or Aeropostal in S.America. Not SQ-like standards, but not terrible either and could certainly help in the creation of a truly global network.