The V35 Skyline is already sold in the USA as the Infiniti G35. It's likely the next GT-R, which will not be badged as a Skyline, will be the Infiniti GT-R in the US market. All previous generations of Skyline, GT-R or not, are not road legal in the USA simply because they were never intended for USDM sale and thus have never passed or even designed to pass any American crash or emissions testing.
ps. old topic!