I think it needs a substantial upgrade. Sure the Mk. III is good value, but it's quickly surpassed by better ships. I hope the Mk. IV will be able to stand alongside the Asp and the Vulture in terms of capability. Given the vessel is specifically for veterans of the game, there really is no need for another low tier ship - That would kind of defeat the point IMO.
I also hope to see a few modifications to the 'pit.
I do not think that the Mk IV will be just an imitation of the Mk III. Frontier knows that the expectations are high for the Mk IV, since a long time