if anything it will just re-inforce steem and make it 'commonplace' -- if i'm honest, i'll be happy if the facebook 'people' stay over there. i can think of a bunch of people who are REALLY friends that i would like here and most of them are here already and have been for the last few years. entry point to a social platform is important and people REMEMBER that, it's your history and what you do and what you have done that makes you standout.
that being said, i'd invest in a facebook coin. no problem at all taking some HODL profits from that ;)