I think it's pretty much try everyone who could play there, and settle on who fits best. If Teddy's back some people have been floating Corcoran, and then really any of the interior guys could do it. The switch to Center went really well for Farmer a few years ago, and Matt Farniok is on an NFL roster as a Center. Developing guys there is not as hard as we've made it look, I think Austin just never bothered developing a backup because Cam was good and any potential backups were more likely to be needed at G/T.
Personally I like the sounds of Teddy at LT and Corcoran at C, but my guess is Nouili or Hixson. I think Lutovsky, Williams (transfer from Northern Colorado), and the losers of the Tackle battles are probably too big to be Centers and we'll find 2 Guards out of that group. Hixson has already played some Center, and Nouili was a pleasant surprise -for the most part.