I have read conflicting reports but the most consistent seems to be that it will be badged as a Scion in the US.
Scion goes more after the "youth" market and generally embraces customization options, etc. Toyota is well, Toyota. The decision will impact the pricing as well as the options. I have a feeling it would do better as a Scion myself. As a Toyota it seems like it would be hard to stand out between the Yaris and the Corolla price and option wise unless it is really high quality, premium focused which I doubt it will be.
I just hope there is some official news on this car sometime soon. It is hard to find anything at all even mentioned besides specualtion.