Although its pretty early to say, but given the circles of trouble surrounding MQM in Pakistan and in London, I can see a siginificant decline in the sphere in which MQM operates, coming down from going national to being limited to a couple of districts in Karachi. Although worse can happen to MQM and PPP too as I am sure MQM will also have enough dirt to spill in case they see that "Mufahimmat" is actually there "Mehroomiyat".
With election 12 months away if the Govt. is not dissolved, Karachi from being a MQM fort will be wide open this time around for the first time since the 60's. Bhutto won hands down in Karachi and after Zia its been MQM since but It will be difficult for them this time aroung to even capture half the seats they did in 2008, especially given that people in GHQ are not happy with them and Zulifiqar Mirza has become the most popular leader since Bhutto (atleast for a day). I think it will be a even split in Karachi and all parties in Pakistan will be there to raise thier claim including Noon, Qaaf, Meem, Wow, Choti Hamza, Bari Ye, Chotti Ye.
The middle class voter which will fall out from MQM will probably fall towards PPP and PTI, though staunch Muttahida supporters will be head on against PP and there would be no seat adjustment. On the other hand, JUI will also pull its muscle to get a couple of seats and ANP will get tough competetion from JUI and PTI, where pathan voters are tilting towards parties which did not have a stake in the bloodied tenure.
Whatever the result is, at the moment, I think no single party from Karachi will take more than even a 1/3 of the seats, splitting the city and perhaps increasing the stakes amongst poltical parties. This could go either way, as it might weaken ghunda gardi of political parties as no one will be strong enough to enforce itself or it could instigate further voilence as more stake holders claim the city.