I like the idea of micro payments, but I don't think they'll take off versus existing ad/subscription models. The problem is economics: the vast majority of people are simply unwilling to pay even a cent. Part of this is people don't know the brand to feel comfortable spending money on random sites (I recall a comic where a user was deliberating heavily on a $0.99 app after easily buying a $7 coffee). Part of this is also the shape of the economy where most people just don't have spare income.

The fraction of people who are willing to pay a cent are likely to be willing to pay considerably more. It is much, much more lucrative to get those people into subscriptions, where they will keep buying -- potentially for years.

So for most businesses, they'd likely earn less revenue via micro payments, which means it's unlikely they'll get widespread adoption.