> Think it's more a case that a Surface-like MacBook Pro would completely cannibalise the iPad Pro and Cook is more fond of the iPad Pro than the Mac line.

I think it's more that retrofitting touch to a desktop OS - any desktop OS - is painful. Microsoft started it with Windows 8 and it's nearly - but not completely - done years later with Windows 10.

I suspect Apple has probably started retrofitting OS X privately, but released the touch bar as an interim solution.