As far as I know, all Mars Sample Return studies since the 1990s have architectures where the samples are captured in Mars orbit and brought back to Earth with another vehicle. It minimizes the mass that has to be landed on Mars and launched again.
If it is so difficult, so time-consuming and so risky after so many decades of space probe development, as describen in the new report, then I feel we have reached the limits of this kind technology. Sure, MSR is scientifically very important. However, whatever the results will be, we will want other samples from different regions of Mars. If we can do the first in the early ‘30s from 10 billion, will we do the second one in the’40s from 8 billion?If we want a radically different possibility, then SpaceX Starship is the only game in the town. Elon Musk hope to send the first cargo Starship o Mars in ’27. Well, Elon time... Nevertheless, it is not more Elon time, than the crewed Starship lunar lander for Artemis 3 in ’26. SpaceX has developed some credibility by now. Either Starship development fails completely (which is a possibility), or SS will land on Mars, maybe in ’27, maybe later, say in ’29-’31. Still, it is not more distant in the future, than the currently expected MSR.Sure, the SS will not be able to come back. However, it can deliver a direct return spacecraft, which is not so much mass constrained than the usual space probes. Assume a cargo-Dragon capsule with a SuperDraco ascent stage for a direct return. It can be developed from the existing Dragon spacecraft without too much difficulty. I am sure, it would cost MUCH less than MSR, as currently envisioned.On the longer term, but still in the first half of the ‘30s (except the case of a complete development failure), SpaceX excepts to establish local production of the return propellant allowing the Starships to return. Unfortunatly, it will happen at a base location, probably far, far away of the scientifically interesting places. Then a large robotic rover with a huge solar panel (no significant wind pressure on Mars) can operate out of that base and reach any place on Mars. (Current rovers are limited by power and communucation.)