Dungeon Magazine
Two thoughts:  First, these magazines are surprisingly content dense.  From the few I flipped through there weren't many ads.  Other beloved vintage magazines, like Skateboarder Magazine, are very ad heavy to support their industry.Second, I feel like a magazine like this, that has good content, might actually be popular with a niche audience as a bonus with a "premium subscription" of another product.  Personally I prefer physical medium still, and I'm sure diehard fans of any niche would be interested in something to hold and collect.