While is possible that individuals of the Governing Body could become a PIMO, I think that the chances of it occurring quite low due to the personality type most of those who become upper management need to be. Clearly most CEOs are nihilistic sociopaths. And normal people, with a reasonable amount of human compassion do give up climbing the corporate ladder unless they were willing to sacrifice their friends, family, even their own personal health for the endorphins of power.
While some point toward Ray Franz as an example (and while I do personally appreciate the work he did latter in his life for all of us) the question must be asked, would he have stayed as a member of the Governing Body if he was not "outed" and my feeling is that he would have, as the books he wrote only were written after his disfellowshiping and in part, to self-justify what had happened to him.
I feel this way because most PIMOs ultimately leave on their own accord (while the time may vary) because the whole Witness way of life, ultimately drives them/us/me mad. And there is the tipping point ... where the pain of shunning becomes less than the mental turmoil that person has because of being 'in', when he or she comes to the conclusion that its time to go.
In the case of Ray Franz, If he had voluntary disassociated and then wrote his memoirs, then I believe he would have been at some time, a true PIMO. The additional advantage he would then had for himself and his books, would be through having the moral high ground, instead of being portrayed as a disgruntled individual or senile old man by Watchtower Society through the pages of the magazines.