Hi, you are asking a good question: upgrade an existing module or write a new module from scratch. The latter is the easier way. But imho, it's not the way you should go. There are plenty of good reasons to upgrade acidfree module (using the same name or choosing a new one doesn't matter here. We talk about "compatibility", not about naming issues). 1. There are really plenty of acidfree users out there who would not like to see the module they use extensively being abandoned. If users find lots of modules being abandoned after one or two release cycles, they may get frustrated very quickly and leave Drupal. Of course, Drupal is a kind of DIY, but without all the John Does, there would not be such a large community. 2. There are already a lot of modules who deal with media in whatever way. We actually don't need yet another module, but a module that has a really strong featureset while being actively supported and maintained.
My opinion is that I should release a 4.8 version of Acidfree that defines 0 node types and simply works with the appropriate node types to offer a unified management interface.
You could solve this issue either by providing an acidfree_legacy.module that defines the content types you have so far defined in acidfree.module or provide a kind of update script (hook_update_N()) that creates new simple node types which replace the 4.7 node types.
I remember a while back that the fact that Drupal does not really have a unified way of dealing with multimedia was a big deal. Are people still interested in this? Or should I just crawl back in my cave and continue plugging away at Acidfree?
Definitely not. There are lots of people interested in media management. Just ask some of the Lullabots and the "troubles" and workarounds they needed for putting out mtv.co.uk. You might also be interested in joining http://groups.drupal.org/file-api. Konstantin