They won't do this, because starting out as non-free doesn't get the same traction. Now that I think about it, it's basically a form of enshitification: draw people in with one deal, then after they're onboard, change it to something less favorable.
The theory is great, but I'm unsure how you execute this.
And if the maintainer wants to, they can always try to go after some of the more egregious offenders.
It is about having a rule that can be enforced when it is obvious to do so.
But I'm all for a good attempt at taking our wealth back either way.
I don't know about any company doing that. I guess some would do so on principle. But I honestly suspect it'd be a cost/risk based decision.
Who knows. But there is seemingly no carrot to entice those with money to give some of it to support the project, so a stick it is.
I like the Blender way of, contribute money = your features requests get some priority. But that only works if the company needs something.