I’m confused why would this happen?

> The IPv6 enterprise argument is 'You might one day have to renumber some devices because some other enterprise might have set up overlapping addresses, therefore you definitely have to renumber everything now, and oh, every time the ISP decides they don't like you, because private addresses are icky'. Obviously that's a hard sell.

If you’re an enterprise you would just get your own IPv6 block assignment. It’s not like they’re expensive or hard to get hold of.

Companies already buy and manage domains, this is no different. Using a domain you don’t own is just plain stupid, same applies to IPv6 ranges.

> It’s not like they’re expensive or hard to get hold of.

For context, apparently a block of 79,228,162,514,264,337,593,543,950,336 addresses (/48) is about 100$ a year.

79 octillion addresses ought to be enough for anybody.

Or you could just say screw it, and use RFC4193, and then all you need to ever worry about is prefix remapping at a few key touch points. Particularly if you don't care about external routing in the first place.