I'm sure the series will top 600+ chapters before it wraps up...
But, as others have mentioned, the possibility of a new series exists. Frankly, I'd like that - watching Naruto do his thing as Hokage, maybe watch events unfold from the perspective of some new young buck comin' up in Leaf Village, something like that.
Moreover, I wonder what Kishimoto-sensei will do after Naruto. This has really been his only project for the last ten years or so - I'd like to know if he's going to do anything else.