Jacob is not a material entity, but rather something metaphysical, which can interact with the physical world. As such, the viewers are unlikely to ever meet Jacob directly in the course of the show. In keeping with the show's continued themes about science and religion, Jacob will be a metaphysical explanation for the Island's mysteries, whereas the science of Daniel Faraday and DHARMA will be the more Earthly explanation for those mysteries. The writers will give the audience two outs, science and religion, but not support one or the other directly. Believing in Jacob will require "faith," whereas the characters and viewers will also be given a hard scientific explanation for what to believe in.
We've seen this play out between Locke and Jack, who are the Yin and Yang of the show. I think Jack will come to be a believer in Jacob and the mysteries of the Island, whereas Locke will come to give up his faith. Thus in keeping with Taoist philosophy, the Yin and the Yang will replace one another.
I think we see the theme play out similarly in Widmore vs. Ben. Widmore was an Other, but may not have had faith in Jacob. He was banished from the Island by his fellow Others, but knew its scientific properties of healing and agelessness, and wants to return to turn it into a business venture. Ben is a man of faith protecting the Island from a perceived threat that would corrupt the sanctity of the Island, which is not for everyone.
Jacob and the Smoke Monster will be the central mysteries of the show. I think the Monster may get a scientific explanation, but Jacob will remain unknown, shrouded in mystery, and require a leap of faith from the characters and audience alike.