Kangaroos basically do everything we do better when it comes to endurance running, be it distances, average speed or top speeds. And they still get to be incredibly energy efficient while doing so with their unique locomotion style. They absolutely could hunt the same way our ancestors did by simply wearing out prey over extended hunts.
Only reason they did not evolve that way over their evolutionary history is, I imagine, that the only prey they could hunt in Australia that way are other kangaroos, which are just as efficient at running away over long distances. But you know, carnivory evolves pretty quickly in evolutionary time scales, if anything survives us I believe they could get there in time. We even introduced camels in Australia for them to hunt that way.
Many herbivorous animals eat the occasional animal. You can find heaps of YouTube videos of deer eating birds, and that’s just what’s been witnessed and recorded by humans. Some scientists in California recently recorded a population of squirrels that is very adept at hunting voles. Kangaroos may have developed their speed and strength to elude their extinct predators, they may also occasionally use it for a little protein and calcium snack.
It seems that kangas and wallabies are indeed occasional meat eaters:
https://iere.org/will-kangaroos-eat-meat/