I use to work for TI who came up with Bubble Memory, and there
     were four main factors effecting it's downfall.

     1. Complexity   2. Physical size   3. Density   4. Cost

Seems that bubble memory was so fundamentally different from other stuff
that it would have required a whole separate effort to SCALE it at anything
close to the rate of either normal magnetic memory or semiconductor memory.
I mean, Bubble memory's heyday was the late 1970's, right?  So it was
competing with 5Mbyte diskdrives (14 inch platters, fragile) and 4kbit to
16kbit dram/eprom/etc.  Now we have 50Gbyte disks (smaller and less
fragile) 64Mbit memories (DRAM, FLASH), approximately a 10,000x increase,
mostly driven my straightforward improvements in semiconductor technology
(Moore's law, etc) and customer demand that wouldn't have helped bubble
memory at all...

BillW