I always imagined that some website/mobile app/service would appear that would let you buy subscriptions for access to multiple publishers at once. I think people have a hard time spending $5 here a month $10 there a month, but would spend maybe $49 for a range of access to sites. I don't know why something like that hasn't taken off yet. You could pick the sites you want access to or they could do a pay out based on…
I think the reason the online music subscriptions have done so well is that their catalogs span multiple publishers, and customers really don't want to subscribe to multiple services. While there's minor differences, you pretty much can get access to any music you can think of.
Otherwise you just end up with some crummy bundling service where you pay a premium for a few things you are interested in, and waste money on the rest of the junk.