The acquisition of SanDisk by WDC is a clear endorsement of its 3D technology, and the fact that now the demise of electromechanical drives is pretty much a given.  I am no expert in Flash technology nor its sector.

How many Flash technologies are there?  Is it one or several?  Anyone knows?

If there are several major technologies which the market has adopted, then the fact that WDC has chosen to go withSanDisk (via acquisition) is not necessarily a nail in either INTC/MU nor NRAM.  But if Flash technology is unified around one standard, then this could be a signal that this new market could get fragmented.