We know that Toshiba are bringing a new NAND fabrication into volume production this Summer:http://www.electronista.com/articles...hones.tablets/
They said Q3, which is July-September. The MBA already uses Toshiba NAND for their SSD chips.
This update could mean double the storage for the same price and I think Apple have to hit 128GB to have any chance of replacing the white MB with the entry Air. If they can hit 160GB, even better.
Same applies to the iPhone, which also uses NAND memory.
They could do the same with the Mini and make it very small indeed - almost Macbook Pro height and leave main storage to Thunderbolt.