I can't imagine that they don't already have plans in mind for a Chapter 3. That ending lends itself to it so well. I got a tooootal Warriors vibe from the last act of the movie, I think it would be perfect if the next (/final?) installment is basically John vs all the hitmen of New York kind of thing.
One of the criticisms I've read of Chapter 2 was that it never really felt like Wick was ever in any danger. Basically too Super Cena. I think they could definitely turn that on its ear by having him constantly be on the run, all the while showing off the same bad-ass gunplay that made the first two movies so fun.