It's tough to say. I don't see a whole lot of top tier backs that I would rather have than Howard, but I also don't see Howard as having the physical skills of an elite player.
His speed and agility clearly aren't elite (not his game) and his power is certainly a strength, but I don't consider it elite either. IMO his best attributes are his vision and decisiveness. Plus that ignores the passing game, which is a HUGE part of the game for a modern RB.
Based on that alone, I wouldn't consider him an elite player. He may still be top 5 RB because I don't see five guys where you can't pick apart their game, and what Howard does, he does well.
So I've effectively talked in a circle. As much of a cop out as it is, I want to see what happens when he gets a better supporting cast. He may use the improvements in talent and (hopefully) playcalling and improve his efficiency (not that he was in any way inefficient as a runner before, but continued growth is always a good thing), or he could slowly work his way to a specific role. I'm not the biggest Howard fan (I like him, but not a must have centerpiece if I was building the team), but I don't have a great track record on evaluating RBs, so take that for what it's worth.