Have you plateaued as a speaker? Fine! You are not nervous anymore, your hands do not shake and you are not comfortable and people regard you as a good speaker but you feel that you are simply stuck somewhere.
This happens to most people in the politics and business world- they just stop learning. But the good thing is that you can improve your speaking skills at any age. Now, an 80-year-old individual will not be able to dramatically become a much better basketball player or golfer but when it comes to public speaking, you can improve. But you have to go back to the fundamentals.
Many people, later in their careers, stop watching video of their own speaking and that is where the bad habits step in. you mays still be comfortable speaking in front of a crowd, but you simply stand up there, rattling through facts, going through details and the motions, and simply failing to form any kind of connection to your audience. That is why you have plateaued.
So do a diagnostic: video yourself, get feedback from others, and try to improve one thing in your next speech. In this way, you will continue to improve with every opportunity.