Sure, I'd like to see that too, but I doubt it will happen any time soon. I think the TV manufacturers are out there on their own, with little prospect of adequate available content for some time to come (few years?).
First of all, Blu-Ray sales have not yet surpassed DVD sales, much less killed it off. Where's the market incentive?
Whatever content becomes available will be heavily DRMed, you can be sure of that. The studios have invested in AAC and BD+ anti-copy protection for Blu-Rays. The simplest solution is to amend the Blu-ray spec and cram main movie onto a BD50. Figure 4x current video bitrate requirement, and improvement in compression efficiency (H265) of around 2x, for increased storage space need of 2x. Since a Blu-Ray main movie just about fits a BD25 (lossless audio tracks aside), it's not *too* unreasonable. You'll need a new player though, obviously, and they'll be few and fearfully expensive.
But look again at the graph, sales are down for optical media overall. Look at past months and it's stagnant at best.
If you're holding out for holographic storage, you'll have a long wait. I don't see the incentive for any such speculative projects. I've read about various suggestions, such as thumb drives; with the new TVs able to recognize/play 4k movies from USB. Really, I think DRM may knock that one out of contention. It'll have to DRMed somehow. What, another DRM scheme? Current ones don't seem to be too popular or successful. But nevertheless anti-copy protection will trump everything else.
So for the time being, I think it will be amended spec Blu-Ray on BD50 or nothing.