hopefully, the cap will continue to work - current thought is that the reason the pressure is unusually low is that the reservoir blew out so much oil it brought the pressure down (!)
at this point, it looks like this leak is approx. the size of Ixtoc - i.e. the biggest oil drilling leak in history
here is a summary article on coastal effects
http://www.nytimes.com/2010/07/18/science/earth/18enviro.html?hpw
I have not seen much on effects on coral reefs or pelagic life as it is not a well studied area of research.