I don't believe just adding a read write head will help HD makers
Hard Drives are old school..
They consume energy hands and fist over SSD.
They are larger
Failure rates go higher as capacity increases (at least in my experience)
And are slower... much much slower.
HD makers have 1 card to play now and only 1... they cost less. But as we've seen before.. those new technology cost do come down eventually.