GTA 6 theories are like mice. Each time you discover one, you should remember there are about 800 more living in your walls. And they're persistent, as I'm learning now that new screenshots have brushed off GTA fans' half-buried suspicion that a Red Dead Redemption 2 crossover is waiting for them.
Generally, I don't find this idea impossible. Grand Theft Auto and Red Dead Redemption are two of developer Rockstar's favorite children, and despite the fact that the franchises take place about 120 years apart, they're narratively linked: rough guys in a rough open-world make morally grey decisions and are allowed to slap prostitutes. GTA has plenty of Red Dead easter eggs, too, like a red John Marston shirt some NPCs can stroll around with in GTA 5.
