the way i see it, there isn't really any 12's in the country who are cementing the position for themselves... Toomuas form even though at 10, has him as the leading inside centre contender IMO.
As for the starting 12's currently:
Godwin, not as impressive as last year but still very promising, not a starting test player... yet
Beale, some very good form but they won't play KB (Kurtley Beale) outside of QC (Quade Cooper), so if KB (Kurtley Beale) is in the team then QC (Quade Cooper) gets dropped and To'omua starts at 10.. Not completely unrealistic, but i still think QC (Quade Cooper)-To'omua is a better combination based on the 2014 EOYT.
Inman, he has been impressive in 2014 for the Rebels, but i don't believe he is a test inside centre. Inman at 12 works for the Rebels, but i don't think an Inman-Kuridrani combination is going to work at test level.
As for some other who will probably see time in the Wallaby squad, Tapuai could potentially earn the spot if the Reds play him at 12 for the remainder of the season and he maintains his form. Lealifano is obviously another contender, but he is starting from scratch and behind the pack at this stage.
QC (Quade Cooper) - To'omua - Kuridrani is the flyhalf/centre combination as far as I'm concerned.