Here's an idle thought... there's precedent for DC having more than one "legacy hero" with the same name operating at the same time. There are at least four human Green Lanterns, not counting the thousands of others. I've seen stories with three or four Flashes operating side by side, all using the name Flash. There was a time when both Diana and her mother Hippolyta were using the name Wonder Woman, at least intermittently.
So even if Bruce returns as Batman in some form, it doesn't preclude Dick continuing to operate under the Batman name in some form. As suggested above, maybe Bruce could be Batman on a more global or cosmic scale with the JL while Dick remains the Batman of Gotham City. Or Bruce could take over Gotham again and Dick could become the Batman of Bludhaven or something. Having two Batmen could perpetuate the myth of Batman as a supernatural creature, if he's showing up in two places at once.