They may not be able to take away the products that have already been sold, but it is entirely possible that they could start severely limiting all new commercial implementations, including software updates, and forcing any free software underground.

For an example of what heavily patented algorithms and implementations can accomplish, take a look at this thread dealing with how ATI feels they must seriously cripple the hi-def output of their video cards in order for them and their VARs to maintain compliance with the terms of the DVD consortium's contract terms:

http://www.avsforum.com/avs-vb/showthread.php?s=&threadid=107908

It is a long thread and ATI doesn't show up and make their comments until 10-20 messages into it, but what they do have to say is really scary. It boils down to anyone who wants to make hardware or software or wants to sell hardware or software that allows DVD playback must not allow DVD playback to a television to exceed a resolution of 720x480. That is a severe (and stupid) limitation, particularly for those on AVS forum who are used to using their computers to scale DVD video up to 1600x1200 and beyond for their high-def televisions and projectors.

If Fraunhofer wanted to, they could probably force all commercial products that support MP3 playback to require some sort of hokey copy prevention scheme or something as equally debilitating as part of the licensing terms for the MP3 patents. You may think it unlikely, but we have the case of Unisys really screwing over the companies that used the GIF image format as proof that this kind of about-face has been successfully pulled off before, and you can plainly see from the avsforum thread that the motivation for those kinds of restrictions already exists in the entertainment industry.

I would much rather have Oog widely deployed before such measures are ever implemented than be pushed into at the whim of Fraunhofer and the copyright industry.