Honda has a much larger worldwide market to sell to. Not so with Buick. China is a large market for them and they are consistently loosing market share year over year.
I don't see a small volume car helping that.
Actually GM is very large in China and while they are seeing more domestic competition there, it's still very strong. The overall automotive market in the US and China seem to be waning but that's overall, not just GM. Interesting article I found yesterday talking about GM in China (and why a merger with Ford might be possible and smart...)
I said from early on that the Kappa platform would have been great to continue under Buick and the Sky model would have fit into Buick's lineup wonderfully as the other Opel rebadges. With sales tanking in 2009 thanks to the limited practicality of the model and 2 seat roadsters in general, once the platform was discontinued and the tooling sold, it was dead. Such a shame for a great platform.