Mostly when we say "medium" we mean something of a pretty high order of complexity: TV, say. Or, saints preserve us, 'digital' (I once wrote a book called Digital Aesthetics: hubris, to believe that there was only one aesthetics for the whole digital realm). These media are constructs, not just feats of engineering but imaginary engines, imaginary in that we ascribe to them a coherence they do not actually possess. Convergence is the tip of the iceberg: so many elements which comprise the digital (and TV) are shared with other media. Take lens technologies for example. There are no analog or digital lenses.
Each medium is already a dozen technologies arranged in a system. To label one assemblage “photography” is almost silly: we have to look a) at the elements from which it is composed and b) the commonalities it has with other media. The term ‘medium’ would be better reserved for, say, a type of screen. And then we might be able to find some new results: coherent light operating in scientific instrumentation, fibre optics and a Jean-Michel Jarre lightshow has certain common characteristics but we rarely understand laser as a free-standing medium like print – and yet the commonalities are significant, as are continuities with pre-laser techniques for disciplining light waves.
(thanks to Kris Cannon for sparking this thought)