AnandTech speculates the first consumer SSD with QLC NAND wil be the Intel SSD 660p. Leaks point to low-end M.2 SSDs with PCI Express x2 interface and storage capacities of up to 2TB.
For the enterprise market Intel is working on 2.5" disks with up to 20TB of QLC NAND flash memory. The chip giant is currently sampling QLC disks to select cloud service firms and OEMs.
During today's discussions about Optane at Intel HQ, one of Intel's partners accidentally disclosed that they were working with 20 TB sized QLC drives in a 2.5-inch form factor - this is most likely a 15mm thick U.2 NVMe SSD. That would be positioned below the Intel SSD DC P4510 TLC-based SSD family that currently offers up to 8TB in a 2.5" 15mm U.2 form factor.