I know this is incredibly premature, but maybe a good discussion can come out of it.
black = staying on the 40-man roster
red = leaving the 40-man roster
yellow = eligible for the rule five draft
green = being added to the 40-man roster
C
Ryan Hanigan
Ramon Hernandez
Corky Miller
Wilkin Castillo
Chris Denove
Brandon Yarbrough
Devin Mesoraco
If Corky Miller ends the season on the 40-man roster, I'm sure he'll be non-tendered. Castillo, Denove, and Yarbrough are all fringe talents, but if any of them have a big year, we could see them added. Even if Mesoraco tanks this year, it's unlikely the Reds would give up on their investment so early.
IF
Joey Votto
Brandon Phillips
Scott Rolen
Paul Janish
Drew Sutton
Chris Valaika
Yonder Alonso
Orlando Cabrera
Miguel Cairo
Kris Negron
Miguel Rojas
Carlos Mendez
Jake Kahaulelio
Jose Castro
Kevyn Feiner
Chris Burke
Eric Eymann
Mike Griffin
Jose Gualdron
Todd Frazier
Zack Cozart
The way Cabrera has played, it's doubtful he'll be worth the option. Miguel Cairo doesn't deserve to be on a major league roster, so I really doubt he'll be around by the end of the season, let alone December. There is a lot of minor league depth, but Frazier and Cozart are the only guys who might get significant playing time at the major league level. Miguel Rojas' bat should prevent him from sticking with a team.
OF
Jonny Gomes
Drew Stubbs
Jay Bruce
Chris Dickerson
Chris Heisey
Juan Francisco
Laynce Nix
Wladimir Balentien
Sean Henry
Luis Terrero
Josh Anderson
Sean Danielson
Denis Phipps
Justin Reed
Danny Dorn
Jonny Gomes' contract might be bought out, and Nix will likely be non-tendered (again). Other than that, we might see Balentien given another shot and/or Dorn finally earning a promotion.
SP
Mike Leake
Homer Bailey
Johnny Cueto
Edinson Volquez
Travis Wood
Matt Maloney
Aroldis Chapman
Sam LeCure
Bronson Arroyo
Aaron Harang
Dallas Buck
Justin Lehr
Tom Cochran
Alex Smit
Scott Carroll
Travis Webb
James Avery
Curtis Partch
Evan Hildenbrandt
My guess is that Harang and Arroyo will be traded by the time the deadline comes around. If not, they'll likely have their contracts bought out. If Dallas Buck turns things around, he could be added to the 40-man roster, but other than that, there aren't many names worth mentioning.
RP
Francisco Cordero
Nick Masset
Jared Burton
Micah Owings
Daniel Ray Herrera
Carlos Fisher
Bill Bray
Enerio Del Rosario
Logan Ondrusek
Jordan Smith
Phil Valiquette
Arthur Rhodes
Mike Lincoln
Jon Adkins
Ben Jukich
Chad Reineke
Federico Baez
Lee Tabor
Terrell Young
Daryl Harang
Ruben Medina
Jesus Delgado
Sean Watson
Jordan Hotchkiss
Aguido Gonzalez
Scott Gaffney
Drew Bowman
Jeff Jeffords
Derrik Lutz
Doug Salinas
Junior Martinez
Jerry Gil
Jeremy Horst
Joe Krebs
Jose Arredondo
Daryl Thompson
I could see Rhodes or Lincoln getting an extension before the end of the season, but I hope not. None of the guys I highlighted are locks to get added to the 40-man roster, but between these four guys plus Ben Jukich, I have to figure they'll round out the roster if no one is added before the draft.