Big fast bowler Boyd Rankin, legspinner Scott Borthwick and left-handed batsman Gary Ballance are all preparing for a baptism of fire at the SCG as England fight to avoid a 5-0 series whitewash.
Australian captain Michael Clarke said he'd be "surprised" if the experienced Prior wasn't also recalled in Sydney, but Cook said rookie gloveman Jonny Bairstow deserved a second chance despite struggling in Melbourne.
Only six months ago it was Clarke's Australian side that resembled a transit lounge.
Now the shoe is on the other foot and England are set to use 18 players for the series.
Cook expects to be leading an unsettled line-up until England start winning matches, but denied Rankin, Borthwick and Ballance would be like lambs to the slaughter.
"We have got this Test where people have the chance to score hundreds at the SCG and take five wickets and a chance to win a Test for England ... and play another Test," he said.
"That's exciting whatever has happened in the past.
"We have been very lucky over the last three or four years that we have been performing and those selected have been winning games of cricket.
"When you lose games of cricket and people are no longer performing and don't justify selection, there will be lots of changes."
Clarke stirred the pot in his press conference on Thursday when he suggested Prior's worth to England was similar to Brad Haddin's influence on Australia.
"Being a senior player with the amount of experience he has, I think they've certainly missed that," he said.
But reinstating the out-of-form Prior so soon would risk making a farce of dropping him in the first place, and Cook said the veteran's numbers simply weren't good enough.
On Thursday it was Prior who helped Bairstow through training, although the apprentice's regular fumbles didn't inspire confidence.
"As (Prior) said himself, he didn't deserve to carry on playing," Cook said.
Australia have already signalled they will look to smash 23-year-old Borthwick out of the attack, just as they stopped spinner Simon Kerrigan's career before it had even started at The Oval back in August.
Borthwick took just two wickets on his home deck at Durham last county championship and as a result his batting has taken over as his main strength.
That doesn't bode well if he is to take over the spinner role from Monty Panesar, who may have played his last Test despite appearing to recover from a calf strain.
Rankin is an imposing presence at two metres tall, however he struggled with his length at the SCG back in November when England faced a CA XI despite there being a place in the Test attack up for grabs.
The Irish-born quick is tipped to come in at the expense of Tim Bresnan.
Zimbabwe-born Ballance at 24-years-of-age is set to replace Michael Carberry, forcing a reshuffle which would see Joe Root open the innings and Ian Bell move to No.3.