Even if the hypothetical BD 4k players support new codecs in hardware, they won't support newer ones, or if the specs change.

Cnet's take on it:

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The "blu" elephant in the room is whether anyone will actually care. Though BD disc sales are still a big source of revenue for the studios, their popularity is rapidly declining. Netflix and Amazon are both offering 4K streaming, Sony offers downloads, and that's certainly just the beginning.

The fact is, 4KBD will look significantly better than any streaming feed. The compression issues we've seen with HD are just as possible with UHD (though how it's compressed is different).

Sadly, most people won't care. Worse, most people won't know there's a difference. 4K is 4K to most people (and if you're reading this, I'm not counting you in the "most" group). That's a battle not likely to be won by an archaic physical media, no matter how shiny it's marketed as being. Think that's pessimistic? How many of your friends still watch DVDs?

http://www.cnet.com/news/ultra-hd-4k-blu-ray-what-we-know/

Team Negative1