Ugh. As it turns out, RB Troymaine Pope was probably rushed back too early which apparently exacerbated his ankle injury. It is now labeled as "a pretty severe ankle sprain'' and he has been placed on IR. FB Will Tukuafu joins him there, not having managed to make it out of concussion protocol. (The recent addition of FB Marcel Reece turns out to have been great timing - thanks, Oakland!).
In a concurrent move, RB Kelvin Taylor (Fred Taylor's son) has been signed from the practice squad to the 53-man roster. (I'll be trying to learn more about him).
Lastly, while details are still vague or nonexistent, it's looking more and more likely that post-season is the earliest that C.J. Prosise may be able to return - if then. : /
Oh, and finally for now, still no mention whatsoever of Alex Collins' status (although fwiw, I just saw him listed along with Taylor as Rawls' backup on the depth chart).
Edited to add: Didn't realize that Taylor was a 6th-round pick for the Niners this year (he also appears to be a decent pass-catcher):