Celibacy is a discipline of the Church and can be (and has been) changed. It is a prudential matter for the leaders of the Church to determine.
The Catholic view is that there is no right to be a pastor. One can inform the Church that one feels called by God, but the Church determines if the call will benefit the Church. (Thus a reformed axe murderer may feel truly called by God to be a pastor, but the Church must discern if this "call" will truly be of service to God's people). I presume it is similar in that a protestant man cannot just demand that he be a pastor - he has to find people willing to give that honor or responsibility to him.