Although it's still no official confirmation the way you'd want, it's more likely to be real than your speculation about NVidia quietly changing their minds, isn't it?I don't see your point. There is no confirmed cooperation between Canonical and Nvidia or AMD. All that the post from Christopher Halse Rogers you have linked to says isThey didn't take back what they said about their cooperation with NVidia (and apparently AMD) - neither did one of these companies.Let us imagine one possibility how that may look like:We're talking with NVIDIA and AMD to get support for running Mir on their proprietary drivers, and providing an interface for proprietary drivers in general.
Canonical: Will you do drivers for Mir?
Canonical: Oh, come on, do it.
Nvidia: No, now leave us alone.
Canonical: AMD, will you do it?
AMD: Are you kidding, we can't even keep up with the Xorg drivers, go away.
See, they are talking about it. "We are talking with them" has about the same amount of information as "We are not planning" or similar phrases: Zero.