Many teams split RB loads among 2-3 backs and I think that's very likely with the Rams. I would highly doubt Henderson is some 'bell cow' RB that carries the ball 300 times. Should he have a role that gets 12-13 carries/game (200 for the season)? Yeah. Beyond that is TBD. I'm not convinced yet they keep Brown because if they do end up taking a RB in the top 80-100 that might make Brown expendable. You don't pay a RB3 $1.1M.
One other thing I'd say is I don't ding Henderson for not being good/reliable in pass protection as a rookie. Almost zero rookie RBs are. Steve Jackson, Gurley, etc.- they all needed time to learn that.
I still don't want a RB until #104 or later. Ideally later.