I have heard from some sources that his bullet proof vehicle was taken away few days before his assassination. Can't confirm it though. Sharjeel Inam Memon (the then Sindh Interior Minister, if I am correct) had ordered to get his bullet proof vehicle taken away.
Unless, you have rule of strict law and its efficient/effective and timely enforcement without any prejudice/discrimination across the board combined with strict punishment, such and many other incidents will keep happening in Pakistan with no one getting arrested and punished.