So it's not really realistic to try to give the latter phases to SOC or other students. It doesn't match their own goals and they don't have the time to do anything but phases I & II.
Who are "they" and what are "their goals"? I don't believe that every student who writes a proposal has a goal of getting code in the Boost release. That's fine by me.
Most people are too well adjusted pscologically to undertake subsequent phases on a volunteer bases.
I don't see how this is a productive statement.
Based on this I really have reservations that GSOC is really useful to boost. Also, given Google's coding guidlines, which explicitly proscribe most of boost and most of C++11, I don't see how Google would find boost a match for them.
I think measuring usefulness by LoC in the release is the wrong approach. I think the default expectation for students to contribute the Boost release is the wrong approach, too. Like I said, not every student has that goal when applying for GSoC funding through Boost.
To me, a larger and more interesting is how does boost have to change to maintain relevant 10 years from now. C++ needs the libraries, but I don't see them coming from anywhere. And boost seems to be getting "bogged down". Like many holy quests, it's seems in danger of becoming a victim of it's own successes.
I think those are issues for another thread.