It is too far away to tell whether Hilary Clinton will attempt the presidency for a third time. However, I think that it is unlikely that she will try in the next election. The main reason is because she insulted the entire Democratic party when she lost. She blamed them publicly. That often leaves a bad taste in the mouth.
However only time will tell because often times people will forgive and forget. It seems that it would take a lot of forgiving for an entire Democratic party to forgive and forget when she publicly blamed them. Also, the party may feel that she would not win the election again. So, they may try for another candidate that stands a better chance of winning.