Sure but in the gap between your changes and the long term change in churn, a third party isn't going to be able to quantitatively monitor future churn rates before they happen.
The solution doesn't fix the problem, because the problem is that quality of business models just plain don't sample for customer goodwill - they measure sales metrics rather than feelings. So the sales metrics are gamed at the expense of the consumer feelings that create the metrics in the first place.
NPS doesn't measure future goodwill (or present goodwill for that matter). Rationally it may have some correlation, but it isn't a silver bullet even when understood and used properly (which it often isn't).
Instead you often get people trying to game their local NPS scores; not quite the same problem, but similar.
The term you're looking for is "brand". Measuring a brand's value is much more difficult than measuring sales, but it's not something new that no company do.
I believe any brand loyalty metric would be helpful if tracked consistently over time. If sales are climbing and loyalty is cratering it's time for the board to step in and ask questions.
More like the dark side of stupid B-school ideas that should be discarded in the dustbin of history. The data is there if one cares to measure them and incentivize properly.
But why would they favor that? They are intelligently blind.
The solution doesn't fix the problem, because the problem is that quality of business models just plain don't sample for customer goodwill - they measure sales metrics rather than feelings. So the sales metrics are gamed at the expense of the consumer feelings that create the metrics in the first place.