At the end of Chapter 3 – Parabellum, the injured John was rescued by the now-scarred Bowery King, played by Matrix costar Laurence Fishburne (there’s still no word on if he’s participating in The Matrix 4).
With both of them having been wronged by The High Table, it looks like they’ll be working together to bring down the criminal organization.
No specific plot details have been revealed yet for John Wick: Chapter 4 yet either, but at least we have an idea of how that story will kick off.