> Unless we find the zoonotic reservoir (which might no longer exist

Which would be shocking given that highly infectious viruses do not simply just disappear after a cross species spillover. Did covid stop spreading amongst humans when dogs/deer/cats got infected? Not only should an independent ancestor branch still be circulating but it should be circulating amongst intermediate species all throughout Asia. It's like a virus pre-adapted towards humans magically appeared and then vanished without a trace, I heard on virologist coin it as the "immaculate infection"