I suspect that, at least if such an answer has good performance, it would be widely used. Quite a few problems with current ML look like some form of goodhearting. So even in a short term pragmatic sense it would be useful. (Of course, making short term goodhearting not in practice a problem is easier than a full alignment solution. 

At least a fair few high status people will look over it and say it looks good. Quite a lot of people will be saying "this is what you should do for AI safety". So there is a decent chance the first project uses this technique, especially if a bunch of rationalist types throw their weight behind it. And after that, its decisive strategic advantage. 

This should be, in fact, a default hypothesis since enough people outside of the EA bubble will actively want to use AI (perhaps, aligned to them personally instead of wider humanity) for their own competitive advantage without any regard to other people well-being or long-term survival of humanity

So, a pivotal act, with all its implied horrors, seems to be the only realistic option

I suppose it would depend on specific properties of the solution; most importantly, whether it makes the AI development significantly more expensive.

If it is not too expensive, projects probably will use it, not necessarily because they genuinely care about safety, but because "safety" is another checkbox they will be able to mark on their product. The greatest risk here is that the version actually implemented will differ from the proposed solution, maybe even become its very opposite (like what happens when software companies try to become "agile").

If it is too expensive, then the projects will probably avoid it. Unless perhaps the rich corporations decide that making it mandatory is a great way to get rid of the competition, in which case they would lobby the regulators to make it mandatory.

(So... does it mean we should actually hope that the solution is super expensive? Not sure, because both things can happen simultaneously: the rich corporations using regulators to make "safety" mandatory, and then creating their own corporate flavor of "safety" that preserves some of the rituals but ignores the inconvenient critical parts.)