Even though Bethesda just detailed Fallout 4's DLC plans, it appears as though the developers are already looking forward to the next installment in the franchise. Ryan Alosio, the voice of Deacon in Fallout 4, has apparently leaked information regarding Fallout 5 — like its existence.
In a now removed Instagram post, preserved by Fraghero, Alosio revealed that Fallout 5 is in preproduction:
Pre-production for Fallout 4 began soon after Fallout 3 released, but it still took a fair amount of time for Fallout 4 to release. Alosio did not detail what Bethesda was doing as pre-production for Fallout 5, but is more than likely a team of developers has been put together to finalize ideas on plot, gameplay, locations and flesh-out other game concepts.
Until Bethesda comments on this, Fallout 5 is not confirmed – but rumored.