Well, I suppose we'll find out tomorrow, but until then, any speculation on what the 'chord' Maria's singing is going to do? My first instinct is that she'll force all nearby Shan to reveal themselves (leave their hosts). But, how desirable would that really be? We don't know the limits of Frank's squid's pyrokinesis, and being swarmed by Shan seems more dangerous than being swarmed by Greys.
Any other guesses, then?
Life can be seen like chess, or pinball. In chess you try to win, thus ending the game, as quickly as possible. In pinball, the goal is to keep playing.
I like chess, but I'd rather play pinball.