[majormajor]

What part do you think opens that door?

Human organ recipients also need immunosuppressants forever, outside of rare cases. This particular case sounds like a very small modification to the source pig, not a pig carrying a human organ.

[XorNot]

I mean I imagine there's research trying to do exactly that: you can identify beating heart cells very early on in embryos, and chimeric organisms are a thing. I imagine someone somewhere is trying to swap out those early cells with human heart cells to see if you can literally grow a pig with a human heart.