Well, Ben (read above where he thinks he's really Adam) and I both have stated our own personal interest keeping the current Tcl-based ACS alive and well. Given that, it is hard to imagine it dying.
On the other hand, ACS 5 and Java will probably appeal to a lot of people. Somewhere around here I mentioned my belief that OpenACS can be a "big tent" project. Those interested in the Java version will undoubtably port it. aD has an interest in seeing it done, at least at the moment. I think I probably want to see it done, too, though I'm not quite sure why - I'm just ornery, I guess. So I'll probably pitch in, too.
But I personally don't want to see the Tcl version go away, and I personally intend to work with it and enhance existing modules and write new ones as well as time permits.
I also recognize that the Java version might help my friends and I land more business. Of course, telling folks that aD made the big switch to the Java/servlet model after Philip left and that we still think "The Book" had it basically right and we're standing on our track record might help us land more business, too...
