I agree with Roberto in that point. If you have to pay a license fee then you loose the "Open" part of the name right there. But what that shows is the concept of what has to become. It must be that easy. Otherwise, like Luigi explains it, you are at risk of extinction; so you must evolve.
Guys, I don't keep statistics of how many times this application is downloaded etc., but it may be interested to see how many times this thing was downloaded 2 or 3 years ago and nowadays. I can see something though since the last time I visited and downloaded OpenACS. It was at the beginnings of 2003 (March I think) and that was version 4.6.X or so, maybe an earlier one. Back then I remember seeing the number of members you show on the front page, and please correct me if I'm wrong; but I think it was about 8K... which is about the same number there is nowadays... So, I guess at some point you may have lost steam.