Not many people agree with this, but i'll suggest it anyway.
Since the classic env. runs side by side with mac os x and will eventually become a application like X11 env. i think brushed metal should be its theme.
Strengths:
a) it is better looking than platinum
b) it keeps that gray that people like
c) more consistency with mac os x
Weaknesses:
a) apple would have to rewrite it's exceptions for brushed metal guidelines.
b) some people want the gap between the two interfaces
c) people still want gray
well it is just a thought