It still stuns me that American automakers don't understand the real reasons why they can't sell cars in Japan and Korea. Yes, the trade barriers are ridiculous, but dropping them wouldn't solve anything. The reason they don't sell cars in those countries is because they don't make cars that work there. A big, heavy, thirsty car is Not a Good Idea in Japan, where small cars/trucks dominate, gas is far more expensive, roads are incredibly narrow, and parking is virtually an Olympic sport in urban areas. Japan has Kei cars (truly tiny things, like Honda's Beat). Small cars like the Cube, Tiida, Fit, and Vitz (Yaris here) dominate. Efficient packaging and attention to detail (not the same thing as build quality in my book) are things that American automakers didn't care about with respect to small cars until recently. Remember the RHD debacle. If it's tough to get people to look at American cars here, how about in Honda's backyard? We have/had loyalties to the Corvette and the Taurus. They have loyalties to the Skyline and the Corolla.
As for Korea, it has its admittedly scary nationalism. Breaking through that could take decades. Hyundai/Kia own 70% of the market as it is.
I think an American brand's best bet for cracking those markets is not the bread and butter mass market, but rather with luxury brands like Cadillac. A luxury buyer isn't concerned about the price of fuel, has garaged parking spaces, and so forth. Just have to bring the whole product range up to par with the competition first. The CTS is a good start.