The concept of a ‘mixtape’ is sound but you need to remember that the mixtape was made by someone FOR someone. Key word being “-one”. You pulled songs that played a memory, pulled a heartstring or solicited an emotion. But all of that focus was on one person (see your image at the top: “for you”.)
I've found Medium as my go-to source for content that I can stumble upon. The ability for you to curate content based upon what I read would help assemble that ‘mix’ for me. Additionally, the use of tagging, very personal for the person doing the tagging, could also help users stumble upon articles that offer a similar interest to them.
I believe the concept of a mixtape you’re trying to achieve is more along the lines of how do “I” create a mixtape for “me” from everything that exists out there. That mixtape shouldn’t be for an aggregate “me”, because I change all the time. That mixtape should fit the mood I’m in today, as a true mixtape would accomplish. Tagging of content could be used to capture not just the keywords representing the story but the emotions you feel behind a story. This would involve tagging from the author of the story as well as from the reader of the story. And this doesn’t need to end at articles, it coudl be used for any content.
As more readers digest, comment, tag, emote and personalize content, “my” mixtape is driven by my mood and the tags or emotions I search. But the key point is that my mixtape can become your mixtape because we both have reverted to our 18 year-old self and have that just-broke-up-with-my-girlfriend vibe going on. And that mixtape MEANS something to me! Now the personal mixtape for “me” has the potential to be a mixtape for the plural “me’s” that are out there and in the same mood or frame of mind.
I love the concept! Just hope I got my points across!