Like many others on this forum I dabbled in Ancient Chinese DBA back in the day, with 15mm Essex and Chariot Miniatures Han, but since these were based on aggravatingly inaccurate source material, they have since been sold off or relegated to fantasy DBA.
In 25mm I think the question is what aspects of the Ancient Chinese do players want to game, since it represents a sizeable investment in time and money...?
Encounters/patrols on the Silk Road/Han Great Wall vs the Hsiung Nu would be good, with a crossover with Back of Beyond - Silk road espionage and Archaeologists etc. and Pulp ranges... a la Indiana Jones / Mummy Returns etc. etc., Water Margin et al.
Much of the popular appeal will probably hinge around fielding your own Terracotta army... You'd have to be a dedicated purist to want to game the Warring States in a larger scale per se... Like others I'd probably be tempted if there was a plastic set to create the bulk of forces around.
However, much of the more popular interest in the Chinese genre hinges on later tech - fireworks, gunpowder etc. which pushes the timeline into the Medieval bracket, not what was effectively bronze/iron-age tech.
That's my thoughts on it at any rate