[Update:Bam! Unlike the MCU, Thanos was already nerfed.]
So, this is actually happening.
We reported yesterday on Fortnite's mashup with the Marvel Cinematic Universe (MCU) and now the event is actually live. If you log into Fortnite you'll find an option for the "Infinity Gauntlet Limited Time Mashup" mode. Click it, and you'll enter the typical 1vs100 setup with one catch -- one lucky person can morph into Thanos. "All" you need to do is grab every Infinity Stone then touch the gauntlet and bam, you turn into a boss character.
While this is a very cool gimmick, I can really see the potential in an asymmetrical PVE mode in Fortnite at some point. If the team at Epic can develop some sort of big bad in the narrative (and they can, based on their wonderful design work), seeing a huge battle play out with all players involved would be great -- like an Evolve, but with a larger playerbase.