I don't see how they won't have to do a major overhaul schematically anyway with the running game. That pretty much tosses out the only real justification for keeping Chaney or Hiestand, imo.
My personal opinion is that scheme importance is often overstated when run blocking and effectiveness is concerned. Imo, most of the effectiveness of a team's run blocking is concerned with whether or not the OLine knows who to block, the technique with which to do that, and whether or not they're strong/mean/tough enough to do it.
Sure, blocking angles matter, but that's not rocket science and there are only so many ways to do it. None of them work if your guys up front can't knock guys off the ball and, imo, just about any scheme will work if the guys up front knock the defense on their cans consistently.
I played Oline in HS and the right side of our line was tough as hell. Shoot, we ran off-tackle on a 4th and 7 and it went 63 for a score - not many teams think their best play on 4th/7 is a 'Wham' right. We wouldn't have tried a 2nd and 1 with the same play to the left and expected much success. Of course, we all had the same coach and all had the same scheme. Difference was in how the players executed.
While I was very disappointed in the run game this year, I think that another year of strength training for the Oline and TE's and some more Tiny Richardson is likely to make a world of difference.
A stud back would make a world of difference, too. I saw Trent Richardson make a lot of long runs after being hit in the backfield and didn't see any long runs from our backs when they didn't get hit until 5 yds downfield. First contact and they were down, typically.