There is no doubt in my mind that physical media will succeed. Streaming is convenient but it will always have issues.
For example: my household has a fairly quick (but overpriced) internet connection through Comcast. However, it would be nearly impossible for me to maintain a UHD stream, why? As I type this, there are at least 10 plus Wifi devices connected to my router. An iPad streaming YouTube + A PS4 playing Destiny + Laptops surfing the Web = not enough bandwidth left for 4K and barley enough left for 1080p.
This scenario doesn't happen with physical media. In fact, my ISP could be down for service and a 4K Bluray would still play just fine. Not to mention, there is still a large number of households that don't have access to high speed internet. In the end, the only thing that will really hold back 4K Bluray is the price. They have to find a way to keep the players and disk cheap.