Persona 3 Reload could have provided a hidden benefit for the Phantom Thieves from Persona 5 and its spin-offs. Since Persona 3 Reload is a remake of a game released a decade prior to Persona 5, the latter has no real presence in-game outside of DLC. That doesn't mean that the game won't do anything for the future of Persona 5 and its protagonists, though. There's actually a fair chance that it could end up being a boost for the Phantom Thieves in the long run. It just depends on what happens in the wake of Persona 3 Reload.