Over the last 3 years, I have seen at least half of the top 10 witnesses staying well within top 10 and never dropping below. With lowering the vote amount, I think based on history, we can say most of the top 10 will remain to be the first preference for most voters.

While I agree that it is still possible for 73 mil stake to take over, it makes it more difficult, slow to execute without notice by others, and risky. Considering the risks 73 mil stake-holder would just stay away from voting altogether.

In the event of an attempt of taking over action by the same 73 mil stakeholder, there would be plenty of time for other stakeholders to consolidate their votes around the top 4-7 as a counter-measure to reject any hostile actions/forks.

This was my logic. But I don't know much. You are right. It wouldn't work.