Heh... The other route is to get the media companies to wise up on DRM in the first place. Not that I see the latter that I mentioned happening in the near future.
Seriously, this is a chicken-and-egg situation right now. OEMs are starting to get more interested in Linux, and one of their big questions will be whether BD playback is important for their products. If the decision is "yes", then one or more player apps would probably show up fairly quickly. Without an obvious market, though, it's not worth it for the player app vendors to make a releaseable product.