I doubt Hilary runs again but if she does there's no way she'll win. She barely won in 2016 when almost all the Dems stepped aside and gave her the nomination. She would have real competition this time and she'd lose.
Simply put, she is a bad politician. She is a smart person and was able to be a Senator (in a position where it was pretty much impossible to lose) and Secretary of State and all that, but being a good electoral politician is a talent and skill and she just does not have it, in the same way that her husband does have it.