> so presumably ability to cross-breed isn't part of the "new species" calculation?

Considering people have interbred jaguars and leopards, and then interbred the female cubs with lions to get a lijagulep, I'm not sure cross-breeding is the gold standard of speciation that gets sold as such in school.

The greatest threat to some of these cat species (the Scottish Wildcat being a prime example) is loss of genetic differentiation through interbreeding with domestic cats.