Sony finally disclosed the full details of the new XQD 4K ready cards. The new E-mount FS7 cam uses that kind of cards. You can preorder them already here:
Sony 128GB XQD Memory Card G Series 400MB/s at Adorama (Click here) and BHphoto (Click here).
Sony 64GB XQD Memory Card G Series 400MB/s at Adorama (Click here) and BHphoto (Click here).
Sony 32GB XQD Memory Card G Series 400MB/s at Adorama (Click here) and BHphoto (Click here).
That new XQD G card line is has a max read speed of 400MB/s, a max write speed of 350MB/s, and up to 128GB of storage. Those speeds make them three times faster than the “N” cards that came before them, and more than two times faster than the second-generation “S” series (Source: Petapixel).
And here is the full press text by Sony.net:
The new G Series is compliant to XQD Format Version 2, both PCI Express Gen.2 and USB3.0 interface are supported on a newly-developed controller for high performance.
The G Series delivers increased read 400MB/s*1 and write 350MB/s*1 speeds, which is three times the speed of the previous N Series cards.
Sony’s unique media technology enables these G Series cards to provide efficient data writing, dependable recording of 4K video while avoiding speed degradation.
The larger capacity 128GB model expands the line-up allowing up to 40 minutes of 4K XAVC Intra 422 60p (600Mbps) recording with Sony’s 4K video cameras. 
<Main recording modes and recording time>
| Product | Resolution | Codec | Wrapper | Frame Rate | Bit Rate | Recording Time(64GB)*3 | ||
|---|---|---|---|---|---|---|---|---|
| G Series | S Series | N Series | ||||||
| PMW-FS7 | QFHD | XAVC-I | MXF | 60P | 600Mbps | 10min | 10min | – |
| HD | XAVC-I | MXF | 60P | 222Mbps | 10min | 10min | – | |
| PMW-Z100 | 4K | XAVC-I | MXF | 60P | 600Mbps | 10min | 10min | – |
| HD | XAVC-I | MXF | 60P | 223Mbps | 30min | 30min | – | |
| FDR-AX1 | QFHD | XAVC S | MP4 | 60P | 125Mbps | 50min | 50min | 50min |
- The G Series is supplied with a dedicated USB 3.0 adapter, which offers convenience and efficiency for professional workflows. It dramatically reduce ingest time by less than half compared to the fastest Compact Flash card*2 even for large quantities of RAW images or data-intensive 4K video files.
Beyond extreme XQD™ memory card
The Sony XQD Memory Card S – Speed Performance Test
Sony 128GB XQD Memory Card G Series 400MB/s at Adorama (Click here) and BHphoto (Click here).
Sony 64GB XQD Memory Card G Series 400MB/s at Adorama (Click here) and BHphoto (Click here).
Sony 32GB XQD Memory Card G Series 400MB/s at Adorama (Click here) and BHphoto (Click here).
Found via PetaPixel and Nikonrumors.