Damien Harris stayed for his senior year, shared carries with Najee and Jacobs and was still drafted in the 3rd round, which is almost as good as one can expect unless you are a truly elite NFL RB prospect.
Najee is not an elite NFL RB prospect, but I believe he is an elite college RB that could work on some things to better position himself to be no worse than a 3rd round selection in 2021.
There are at least six RBs that will get drafted in front of him this year, so he is probably at best the 7th RB on the board. The 7th RB was the last pick of the 3rd round in 2019, so that is probably his ceiling for the 2020 draft and his floor could be anything. I realize all drafts are not created equal, and there are probably 2 - 3 RBs that are pretty highly coveted that could make RBs go a little earlier this year versus last year. Regardless, his ceiling could be early 2nd round in 2021 if he can improve some of the aspects of his game.