Slava created an interesting language but I never saw an explaination of why he moved away from Factor. He just stopped (writing and caring ?) about it.
Still, it's so strange to me: not only Slava disappeared, but most of the original authors stopped participating in the development and even stopped blogging about Factor. See http://planet.factorcode.org - most blogs have been abandoned for years, some of them are dead links... Also, I have not found any public announcement about who will maintain Factor in the future.
I really like what I know about Factor, and I have tremendous respect for Slava and others who created this language. I looked into the code a little bit, and it looks a very well-thought and very serious work, and I have no idea how they could create it in such a short time.
Still, you can't manage a project like this. No matter how great the language is technically, I won't start using it for any serious work if I don't see any vision, any chance that the project will not get stuck in this stage. I really hope that Factor will overcome these challenges. It would be so sad to see such a brilliant piece of work to be abandoned.