At the end of John Wick 3, Winston appears to betray John by shooting him, and John falls from the roof of the Continental to the street. The betrayal turns out to be a ruse. John survives, is carried to safety, and ends up with the Bowery King, and John, Winston and the Bowery King agree to join forces against the High Table.
Why does the shot matter? In my opinion, the scene works because the film has spent its second act making Winston's loyalty a live question. The Elder's price for forgiveness was Winston's life, and John cut off his ring finger as a sign that he would pay it. So, when Winston raises the gun, the audience has just been told that the one man John trusts is the man John was ordered to kill.
The ruse also fits the corner the characters are in. The High Table has stripped the Continental of its protected status, and it has sent Zero and a team of enforcers after both men. That being said, the film does not spell out every step of Winston's plan, so how the shot was meant to work is open to interpretation.
The ending also tells you where the series goes next. The Continental has been punished, John is hidden with the Bowery King, and the three men are now allies rather than separate pieces. That sets up a war with the High Table in the next film, john wick 4, where the Marquis destroys the New York Continental and punishes Winston. The finale of Chapter 3 is a setup rather than a resolution, and I think that is the right choice for the middle of a larger story. For the bigger picture, see the john wick timeline and the notes on the high table john wick.
