The later reincarnation of Dungeon and Dragon magazines that coincided with the release of D&D 4th edition were exactly this, you could purchase a D&D Insider (

The later reincarnation of Dungeon and Dragon magazines that coincided with the release of D&D 4th edition were exactly this, you could purchase a D&D Insider (iirc) subscription that included these two magazines and some online tools for things like character creation. Sadly those both ended with 4th edition, but just yesterday Arcadia magazine was launched through Patreon - https://www.patreon.com/mcdm https://www.patreon.com/mcdm (I'm not involved, just a fan!)