The scariest link there - I've said this before, but there is no harm in repeating it - is that Pakistan probably has both, we're sure about their nukes and we strongly suspect they have a BW unit.
IS gaining a foothold in Pakistan gives them potential access to weapons of a totally different grade than the ones that they have today.
If that should happen and these weapons would be brought to a readiness level associated with an imminent attack or if - which I hope we'll be able to avoid but which you can't rule out entirely - an attack with such weapons would be carried out the degree and scope of response will be such that the map of the regions involved will be totally redrawn.
As soon as terrorists cross the line where all-out war against them is justified and the cost to society is one we are willing to bear (and we're far from that, right now the most people can be seen to support is to drop some bombs from a high altitude) it will be 'game over' in a relatively short time with respect to the first level of confrontation and after that we will have a repeat of the aftermath of the Iraq war but on a much larger chunk of the globe.
The world is a tinderbox and way too many idiots have matches.