This seems like an odd move for a gaming company. But I wonder about its implication for streamers who deal with DMCA takedowns for playing copyrighted music. Perhaps a scheme where partnered streamers are granted limited license to play music from across Bandcamp while they stream games from the Epic Store.
For a lot of indie games, it's not uncommon to see the game soundtracks available for download on Bandcamp. Part of me wonders if they could potentially integrate soundtrack bundle downloads with the Epic Store a little better.
I'm assuming that, while the store will also remain separate, there will be at least backend ties into the Unreal asset store. Could see them trying to work with some music creators to set up licenses for people to buy to add their music to Unreal games.
If you have a platform that artists allow purchasing of their music through, you can extend it to allow customers to sell/license songs in their games (developer) or buy snippets of song in Fortnite (gamer).
Sound Cloud would achieve these features too, and I am certain they considered more than just Bandcamp, as well as kept everyone under NDA during the shopping around.
I think of them as primarily a gaming tools company.
Fortnite and other games are really just Unreal Engine advertisement vessels that got successful in their own right and now serve that purpose plus making lots of money on their own.