The sad part is that this commoditization of content ends up affecting the quality content, that will probably end up becoming a niche market. Charge per content and the user will bounce, charge per month and you have to be the biggest because of network effects (try recommending a series from Amazon Prime to someone who subscribes to Netflix)
There is a trend to use ads disguised as content ("People are using this secret trick to earn mad $$ in [oddly specific location, close to you]"), or intertwined with content that is yet immune to ad blocking(like ads in the middle of youtube videos/podcasts), but that has a higher production and negotiation cost, it will probably not be a market as big as ad networks.
EDIT: Just remembered about ads on smartphone apps which are a viable option due to the lack of user control over hardware and software. There are some solutions, but these are much harder than installing a browser extension and thus not as widely adopted.