The main problems with Boost which are causing its decline are these:
1. Boost isn't sexy any more.
Niall, this is a very rich topic. I came late to C++ and even later to boost. My experience has been that boost is a trusted and established library with extremely high quality and a huge user base in the community. Making a boost 2 would be a massive endeavor. I shudder to think of refactoring the lines of code, carefully crafted for their purposes --- yet non-trivially intertwined with each other amidst massive header-dependencies that somehow keep boost up and running. It is simultaneously a wonder, an old work-horse, and some might even venture to say outdated. I would like to see some kind of new boost, or a face-lifted boost, especially with * a standard build system (if there even is such a thing) * a dedicated configuration for bare-metal OS-less programming. But to replicate and improve on boost would be an endeavor of huge development power. I could go for it, but it would be massive work.
3. All the interesting new C++ 11 libraries you find around the internet have zero interest in trying to join Boost, with a very few honorable exceptions. That speaks volumes, to me at least.
I once wrote an interesing library, and boost contacted me. We went on from there and have enjoyed a productive development for almost 3 years now. Let's get back to the "boost isn't sexy any more" part. I believe that *neither* boost nor C++ are sexy any more. I do not say this with sarcasm or cynicism. Rather, I say this with wonder and marvel at how boost and C++ have catapulted our ability to program to a level of abstraction that we previously only dreamed of. I do not know if any kind of boost 2 could re-vitalize C++ or if any kind of C++11 or 14 or 17 could re-vitalize boost. And I don't know if any re-vitalization is actually needed. C++ is one of the top three languages for development in the world! C++ is here to stay for a while. It might simply be that both boost as well as C++ are maturing. The C++ language is 30 years old. Maybe boost and C++ are reaching more of an institutionalized status, and less of a sexy status. Well, those are my ramblings. I guess I am satisfied with boost as it is. But I could also work on a new version. But by the time a new one might be done, I might be close to retirement. Either way, I really appreciate your energy --- positive, provocative, thought-provoking. Keep going! Cheers, Chris. P.S. If you would like to turn a whole generation of new programmers onto C++, look at the embedded-systems community. Those OS-less developers (predominantly electronics freaks) are cutting code in plain C and assembler --- 50 year old methods. We could bump them up 40 years with a turn-on to C++11 (which I did in my recent book on Real-Time C++).