Though packing 4K content onto a Blu-ray disc should be possible, there's a lot to think about before going forward.
At this point, the 4K revolution seems inevitable. The industry is pushing for it hard and if pricing can get lower, there's no doubt that people will start to make the switch. After all, this isn't something you need to wear glasses for or even buy extra speakers for – it's a better looking picture.
Content delivery is a problem though, and it's one the Blu-ray Disc Association has been pondering. The format has had a good run thusfar, and the BDA would like to keep that going once UHDTVs really start to penetrate the market. There are three things they're looking at in regards to 4K Blu-rays: technical hurdles, demand and the effect that 4K discs would have on current Blu-ray fans.
Creating 4K Blu-rays would also segment the market if the discs aren't compatible with old hardware. Folks who want to watch a UHD movie would have to ensure they had a 4K compatible player and disc. It's not hard to imagine the confusion of the general consumer. That's something that could be solved with backwards compatibility, or simply by bundling a traditional Blu-ray with a 4K Blu-ray.
What happens with the initial rush of UHD hardware will be telling, and will have a big influence on the Blu-ray format moving forward.
Source: Big Picture Big Sound