In 2015, Blu-ray and DVD sales fell 12 percent while digital-media sales jumped 16 percent, following years of similar trajectories for both categories, according to figures from the Digital Media Group. In fact, digital sales also surpassed physical-media purchases last year, clocking in at $8.9 billion compared with $8 billion. And let's not forget about streaming subscriptions, which jumped 20 percent to reach $5.7 billion. In other words, 4K Blu-ray is launching at the worst time for disc-based media since the advent of DVDs.