I'm going to amend my prediction to give more variance, since there are so many unknowns: 2-7 through 6-3 are what I consider the safest prediction interval. There are just so many variables: The new arrival of Jet, Sherm, the rookies, the new center Weston Richburg, moving Solomon Thomas back on the inside on pass rush downs where he belongs, Foster only being suspended two games, the return of Malcom Smith (who was, by all Bay area sports writers accounts, having a really good off season before the injury), the return of Pierre Garçon (who never played with a competent QB on the team, being injured after 8 games), a new right tackle (McKlinchey) who is a better scheme fit, but perhaps not as good a pass blocker as Trent Brown (but definitely better run blocker), the loss of Dantae Johnson (addition by subtraction... sorry Seahawks fans but he was terribad last year), and of course, how far will Garoppolo be able to take the offense.
So yeah, there are just too many unknowns.
So splitting the difference between my expected boundaries, give them a 4-5 +/- 1 W and 1 L start.