In 2013, Leonard Susskind and Juan Maldacena proposed this idea, so what was it? It was that a non-traversable wormhole (the Einstein-Rosen bridge) is, in a sense, equivalent to two entangled black holes.
The connection between ER and EPR is fascinating, because, both of these papers were published in 1935, however, they were not related at the time.
Susskind and Maldacena propose that the outgoing and incoming particles in the AMPS firewall are connected by wormholes. They are not independent systems. Whether or not there is a firewall depends on what falls into the other black hole. However, this makes it difficult for entanglement on the other side of the event horizon. This is because traveling faster than light is not possible.
More generally speaking: any entangled pair of particles are connected by Planck scale wormholes. In this view, the geometry of spacetime and gravity is determined, in a way, by entanglement.