But the coach has not completely ruled out a switch to either inside or outside centre.
Folau was Australia's only threatening ballrunner at ANZ Stadium and it's believed he would like to be closer to the action.
Kerevi was dropped for the third Test against England as Cheika opted for a secondary playmaker in Toomua, but he offers enough thrust to be the early favourite.
"We could go for two ball carriers as opposed to two playmakers as we did against England," Cheika said.
As for Giteau, the 33-year-old is likely to likely to be sidelined for up to two months.
"Matt's got a bit of a break in his leg, at the top of his leg I think and a bit of a fracture in his ankle, so he's done a pretty good job on his leg," Cheika said.
"He's disappointed but he's also very realistic.
"He's a pro, he still knows he's got to get himself right to get back to his club commitments (with Toulon) later in the season so that's what he will be doing."
Wallabies vice-captain Michael Hooper feels for Giteau, who sacrificed hundreds of thousands of dollars from his French club contract to have one final tilt at winning the Bledisloe Cup.
"It sucks for Matt and for the wider team," Hooper said.
"He's such a vibrant character with him and Drew (Mitchell) and the other guys who come back.
"For him to go out so early in the game is really tough to take, so it'll be disappointing not having him at full fitness."
Horne also faces surgery on his shoulder after it popped out trying to tackle Israel Dagg and is unlikely to be available until the spring tour.
Toomua was concussed after getting his head on the wrong side of an attempted tackle on Beauden Barrett.
"I would say [Toomua] will struggle to be available for this week after he took a pretty heavy head knock," Cheika said.
"We'll just go through the recovery protocols for the head knock and see how he stands."