While rovers have made incredible discoveries, their wheels can hold them back, and erratic terrain can mean damage. There is no replacing something like Perseverance, but sometimes rovers could use a leg up, and they could get that from a small swarm of four-legged robots.
According to the article they would be supplemental to the rovers, not as a replacement. So I’d imagine they’d be able to retreat into some sort of storage on the rover where they could hopefully be air cleaned automatically.