This, plus who knows how long we can rely on the Turing test.

It may scale when you think it as putting yourself or your reasoning consciousness as stake in the system (instead of hardware or financial capital) by actively contributing human deducing capacity and taking responsibility once every 2-4 weeks synchronously. Android and mobile validation apps may also do their part in easing and scaling this thing to more users because of the nature of synchronous validation parties. I reckon Idena is among the most reasonable options when considering the "Decentralized Identity Trilemma".