But Marsh's stunning century on the opening day, in his first Test for four years, has made him very tough to leave out which means someone else will have to make way unless they opt not to bring Green straight back in.
The spotlight has again returned to Warner after his twin failures at Headingley where he twice edged Stuart Broad to slip from around the wicket, making it 17 times he has now fallen to Broad.
However, that followed some useful contributions earlier in the series, led by the 66 on the opening day at Lord's in tricky batting conditions, although he was dropped in the slips on 20. His overall Test average since 2021 remains 28.17 and that includes the double century against South Africa at the SCG.
"You keep all options open," Cummins said. "We've got nine or 10 days now, so we'll take a deep breath. We'll go away for a few days.
"But everyone comes back into it. Greeny should be fit for Manchester. Josh [Hazlewood] will be back in there as well. So we should have a full roster and we'll have a look at the wicket and have a chat and work out the best XI."
Marsh's third Test century, all of which have been against England, came from 102 balls while he also chipped in with a couple of wickets.
Cummins conceded he would be difficult to omit. "Yeah, it's possible but, I mean, it was a pretty impressive week, wasn't it?" he said.
Warner has mapped out his retirement plan, announcing earlier in the tour that he hoped to finish against Pakistan on his home ground of the SCG in January. Prior to that, the original Ashes squad was only selected up to the end of the Lord's Test which raised further questions over Warner, but he did enough in the early matches to dampen talk somewhat.
The situation Australia now find themselves in is not dissimilar to what happened on the 2019 tour when Marnus Labuschagne performed so well as Steven Smith's temporary replacement that someone else had to make way for Smith's return. On that occasion the fall guy was Usman Khawaja.
Meanwhile, Cummins indicated that he remained on track to play all six Tests on the tour which he had stated as his aim before the World Test Championship final against India. He is the only Australian quick to play all four matches to date. England have had Stuart Broad and Ollie Robinson in all three of their attacks, but the latter is now under an injury cloud after suffering back spasms at Headingley.
"I feel great, actually, probably better than I would have hoped," Cummins said. "I don't have any niggles or injuries. So fingers crossed, should be sweet."
Elsewhere in the squad, Michael Neser has been released to play the next round of County Championship matches for Glamorgan while Josh Inglis, who flew home after Edgbaston for the birth of his child, will return on Friday. Jimmy Peirson filled in for him as reserve wicketkeeper.
Australia's players will break up for a few days and make use of the longer gap between these two Tests before beginning preparations for Old Trafford - the venue where they were able to retain the Ashes in 2019.
Cummins gave a succinct response when asked if he felt England's win would shift the momentum in the series. "No, not really. It's 2-1."
Andrew McGlashan is a deputy editor at ESPNcricinfo