I think the key here is going to be variety - within reason. Having just one contribution to each category of vehicle will lead the GZG hobby to a bit of stagnation. As the supply of good 15mm vehicles is still pretty limited, I do hope that GZG will add a few more designs to each of their categories.
Of course they have done wonderful things for adding variety by including the bits (grav emitters, guns, etc). I would like to see them make the walker legs available seperately as well. These all allow us to take vehicles from other companies and tweak them, widening the variety. I know that some T-55s will be getting some grav emitters soon to make them into low-tech grav vehicles. I would love to be able to give some WW2 German Scout Cars legs too.
-Eli