I know my massacre question sounds sinister… what if a nut succeeded?
There are several almost prophets I can think of – BKP has been a dominant figure for some people, McConkie another, Talmage, Eliza Snow, N Eldon Tanner, Widtsoe, Cowdery, Pratt, Hyde… all of these have had big effects on the church without reaching the very top.
Pres McKay was a good president IMHO, better than some who followed him. Lorenzo Snow underrated. Some stick out more than others. Some would not have been my first choice.