The Malignant, a leaker, has posted a NAND memory spec sheet which reveals Apple will offer 32 GB, 128 GB, and 256 GB of storage, with Toshiba supplying the latter.

Apple's removal of the 16 GB storage option is also supported by this leak, as is the idea that 64 GB won't be available. The 16 GB option has been considered largely obsolete for a while and some users feel the same way about 32 GB of storage.