Unless Trump were to say that he isn't running in 2024 you're not going to see anyone toss their hat into the ring.
Trump is wise—a lot can happen in the next year and a half. He should kick back and see what the lay of the land is like. Possibilities are endless. A) Civil War (Red vs Blue) Long Shot. B) Small war (Real Possible in Middle East) C) Big War with Russia or China or North Korea and Iran (Also possible). D) Assassinations (sadly possible in our age). E) Terrorism like 9-11. (Also possible) F) Big Natural disasters like Earthquakes, Floods, Hurricanes, maybe Yellowstone will blow? Change is one thing that is in the air!
Which means the announcement is still more than a year away. I guess that could be considered "not too distant future".