I agree with @spacecadet 100%. The cassette revival makes no sense. The appeal was they were portable and took up less space in your room, but they provided crappy sound back in the day, and there's no reason to believe it's somehow better than anything else that exists today. If you're going to go to an old format for quality, go analog vinyl.
That being said, I did mostly collect cassettes over vinyl when I was younger. I will probably get whatever Scandal puts out just to have it (may even frame it for my music room because it will be so odd).
What would be cool is if they treat this like many of us did back then and have it created as a personal mix tape by the girls. It could be their own songs or someone else's, but it would show off their personality in the process of what they would like us to hear. Even cooler, go the KISS route and have each girl make up their own mix tape. Personally, I would love for the cassettes to contain outtakes or demos. That would definitely feel old school.