For Version 12, I would love to see some impovements made to the Theater View. I think the Theater View interface is lacking a bit when compared to programs like Meedio, Media Portal, and Beyond Media. However, those programs can not even begin to compete with Media Centers ability to organize, tag, and play your media. Basically, I think Media Center would be the ultimate Home Theater front end if theater view was improved. More specifically, an interface that more closely resembles other HTPC frontends, the ability to rate your music from the theater view, support for 3rd party plug-ins for things like weather, movie showtimes, ect.., ability to move songs around in Playing now, simplfy how music is added to playing now, like one button press to select a song instead of having to open a submenu to select a song, the ability to size theater view to fit on the tv, Built in DVD support, instead of needing to have PowerDVD or another program installed, and a DVD player that supports advance features like VRM9, and though I have not played with yet, but it sounds like improvents to the DVR functions would be great too. And probably a few more things that I can't think of right now.
Reading through the forums, this does not seem to be very high on the list of improvements most people would like to see in MC12. I am not sure how many people are using MC for an HTPC frontend, but in my opinon the only thing the other programs have over MC is the interface. What MC has under the hood though is just leaps and bounds better then anyone else. It seems like a market MC could really make a big impact in.
I hope some focus can be put on this, but even if that is not the direction where JRiver is heading , I am sure I will still be using Media Center for a long time for all it's other great abilities.