I think the real test will be September: how many students have moved across to running their Social Networking through Plus, as opposed to Facebook or something else.
Once terms begins I suspect people will form around one network or another as their primary tool, so if Plus hasn't managed to get full social groups across and active by then, they may well default to Facebook as their primary social network for organising and sharing. Alternatively, I could see Hangouts managing to grow as a chat/skype substitute even if social groups were generally staying on Facebook as their Events and Sharing site.
Once terms begins I suspect people will form around one network or another as their primary tool, so if Plus hasn't managed to get full social groups across and active by then, they may well default to Facebook as their primary social network for organising and sharing. Alternatively, I could see Hangouts managing to grow as a chat/skype substitute even if social groups were generally staying on Facebook as their Events and Sharing site.