There was a great article in New York Magazine covering the background here and the possibilities.
https://nymag.com/intelligencer/article/coronavirus-lab-esca...
It turns out we've been doing "serial passage" research for some time, which is where we leverage natural selection to do our genetic engineering for us, rather than manually editing genes. This is how we engineer viruses to jump species - on purpose.
> They did it using serial passaging: repeatedly dosing a mixed solution of mouse cells and hamster cells with mouse-hepatitis virus, while each time decreasing the number of mouse cells and upping the concentration of hamster cells. At first, predictably, the mouse-hepatitis virus couldn’t do much with the hamster cells, which were left almost free of infection, floating in their world of fetal-calf serum. But by the end of the experiment, after dozens of passages through cell cultures, the virus had mutated: It had mastered the trick of parasitizing an unfamiliar rodent.
In fact, "we" (meaning humanity) have even been experimenting with serial passage into humans.
> A few years later, in a further round of “interspecies transfer” experimentation, Baric’s scientists introduced their mouse coronavirus into flasks that held a suspension of African-green-monkey cells, human cells, and pig-testicle cells. Then, in 2002, they announced something even more impressive: They’d found a way to create a full-length infectious clone of the entire mouse-hepatitis genome. Their “infectious construct” replicated itself just like the real thing, they wrote.
The whole article is really worth a read.