Frank Gore is getting 16.5 carries per game and gaining 4.9 yards per carry, with an additional 2.25 passing targets per game, 4.33 yards per target. This is out of a total of about 24 RB carries per game that the 49ers divvy out, about 2/3rds of the running load and 9/16 RB passing targets.
With the return of Brandon Jacobs and the impressive play of Kendall Hunter (esp. in the passing game), maybe its about time to cut Gore's workload by 1/4th or so to ~12 carries a game, 50% of the workload. The remainder would be shared by Hunter and Jacobs based on the situation (i.e. short yardage for Jacobs) . On a per carry basis, Hunter is playing like Ray Rice (#2 DVOA in NFL), and was 10th in DVOA last year as a receiver.
As a result, I think its time to cut down on Gore's carries to keep him fresher for a long period of time. If you cut him down to 12 carries/game from here on out, he still finishes with 1,033 yards on 209 carries, maybe more with fresher legs, maybe more with the 49ers playing with the lead more. In place of that, you have Hunter in more plays as a more explosive receiving presence and game-breaking ability out of the backfield...Gore has never been a great pass-catcher. You also reduce the chance of Gore getting injured -- he'll be fresher for the playoffs.