This article contains speculation, information which has not been confirmed by a reliable source. The game is still in development, and all information is subject to change.
Dredge is just one of perhaps several cities that will act as hubs for players. In Dredge, it seems reasonable you can expect to be able to shop for new gear, trade, meet up with other players, and manage your equipment, crafting and other activites that don't require venturing out into the world.
From the official site:
As the Accord’s main source of crystite, Dredge has become a thriving and crucial strategic asset. Home to daring crystite extraction teams, it’s proximity to the Melding has also made it a hub of search and rescue operations, as well as the target of relentless Chosen attacks that keep the Accord busy. But the allure of plentiful crystite, and the convenient habit of Accord forces ignoring anything that does not impede it’s production, has also made it a sanctuary for criminals, rebels, greed and sin.
To many, Dredge is the best place to help forge this new world, to find new clusters of crystite or find and help new survivors trapped in undiscovered Melding-free fragments. To others, however, it is ground zero for the battles against the Chosen, or a loose and dangerous place where a bold marauder can skim crystite by guile or force and spend it all in an evening of debauchery. Either way, Dredge has become a vital artery in the construction of Ember and the survival of the Accord.
Located in the shadows of the cliffs surrounding the Smokestack area, Dredge quickly became humanity’s most viable source of remaining crystite. After the crash of the Arclight and the resulting Melding disaster, the Accord quickly moved in to Dredge and set it up as its primary crystite extraction operation. While Dredge provides the vast majority of the crystite for the Accord, mercenary armies are relegated to scrounging and fighting over smaller deposits that still exist in New Eden and some even risk venturing inside the Melding to meet their needs.
How ever in Firefall Open Beta they removed most of the leftover Meld and Dredge went away with it so its not accesible, but it might be back after a few years.