I don't think it is possible to provide housing to anyone everyone who is fleeing from FATAs. There are hundreds of thousands already living on illiegal occupied lands in Karachi, what have they done wrong? Everyone will have an excuse why they should get housing from Sindh govt etc., it will open flood gates of corruption (as if we are limited now :D).
It should be Fed govt's responsibility to relocate them to different cities and stop the crowding in one city. Fed should redirect people coming out of FATA to other areas instead of burdening one city. May be govt can build few refugee shelters for the people.
Technically you are right on that one.. but if FEDS are doing nothing then the local govt should do something about it..
People who are fleeing from FATA can be provided with the Refugees Camp.. and that will affirm their temporary status..