At the very minimum 2 years.
Egghead's conclusion and the escape to Elbaf will take at least 10 more chapters.
The Elbaf arc alone will surely have 50 chapters or more (50 chapters is actually the bare minimum).
So that alone makes 60 chapters and Oda's current pace is 30-33 chapters per year.
In reality it will probably take about 4 years, since we know Oda probably has a few more stuff he wants to cram in before.