But we can't just stop investing effort in C++03 maintenance. We have to officially drop C++03 at the Boost level, meaning, refuse to compile Boost with C++03 at all, or make it difficult, or at least make it choose an intelligent default that is never C++03.
As Beman suggested so many years ago now, it's long overdue for a separate Boost v2.x release which is shorn of the backwards compatibility and undermaintained libraries. I'd make it C++ 17 by default, too, as surveys suggest people are jumping straight from C++ 11 to C++ 17 and not stopping at C++ 14. People can keep around Boost 1.x with the existing libraries as long as people want it. Let's just break free of the ancient cruft already. And before anyone asks, it would be on each individual library maintainer to do the work to put their library into Boost 2.x. Which should be 100% cmake, incidentally. Niall