According to TechTastic (opens in new tab) - a blog that has consistently leaked big upcoming handsets in the past - has a source that has supplied images of the phone and a spec list. The photos and specs listed out suggest the Xperia XZ1 will be remarkably similar to the Xperia XZ.
Much same, such Xperia
That will be joined by 4GB of RAM and 64GB of onboard storage. On the front is expected to be a 5.1-inch Full HD display, the same size and resolution as the Xperia XZ.
On the rear is expected to be a 19MP camera while the front will have a 12MP shooter. Both cameras will be able to shoot 4K video, but as the screen isn't a super high resolution it won't be useful to watch back on your phone.
Other camera features are currently unclear, but it may be that Sony will include the 960fps slow motion burst feature from the Xperia XZ Premium and Sony Xperia XZs that allows for improved clips to slow down.
The fingerprint sensor for the Xperia XZ1 looks to be on the back of the phone, rather on the side power button like in recent iterations of Sony phones. Previous Sony phones haven't had fingerprint sensors for the US release either, so it'll be interesting to see if it makes it to the US for this new release.
We expect to see the release of the Xperia XZ1 at IFA 2017, which kicks off on August 30.