Sony's CEO, Kaz Hirai, has been speaking to Japanese media, with market share and breaking into the U.S. in particular on the table. With Japan and Europe accounting for around 60% of Sony's smartphone sales, and it seems priority one for Hirai is to maintain and build on that: 

So, if you read between the lines, you could argue it may be some time before we see the Xperia Z1 in the States. If at all. That would be a shame, since the Z1 has a lot going for it, and it's a match for any of the high-end Android devices out there right now. But Sony wants to keep making money, so perhaps it makes sense for them to hold off on trying to crack America for now.