Don't fix what isn't broken I say.
The most they can do really is get meatier speakers really. No point in upgrading the decoder to support DTS-HD and Dolby TrueHD etc because the optical/coaxial cable doesn't have the bandwidth to feed it. They could shove a HDMI port on it which could in turn extract the audio I suppose and then pass the video on again but that's getting fussy and it would have to be implemented properly in the PC's hardware too, something a huge majority of us can't be bothered to do. Plus most people don't own a player that accepts high-def media yet anyway.
Until Blu-Ray really takes off in a big way to a point where your average joe has one, I don't think they'd bother implementing such a system.
At the end of the day they will take anything you can throw at them. They have a decoder capable of decoding any bit stream you can throw at it and it includes a direct 5.1 input, something a lot of surround sound recievers still don't have.
They're an excellent set of speakers for the money and they can be found cheap enough now anyway if you're prepared to shop around.
Sorry to widdle on the bonfire, but why upgrade something that doesn't need upgrading?
I have a set and I can safely say now, they will cope with anything a huge majority of people plan to do with them.