What will happen to the portions of the Boost library that are incorporated into the new C++ standard?
Will they continue to evolve and any changes be reincorporated into the standard which follows C++0x?
They already do. Some of those libraries have additional features in the boost version. For example, the smart pointers library have intrusive pointers in addition to other standardized smart pointers. There are still propositions for other smart pointers implementation in the mailing list. Another example is the random number generation library that have more generators in boost than the standard (at least from what I see in n3290).
What happen is that once standardized, the library is modified to match the standard interface. After that, the author (or any other contributor) can continue to work on the library.