(APSW author here).  I haven't ported to the new Python 3.3 Unicode handling yet but it is on my todo list.  The PEPs and doc said the C API would remain backwards compatible.  The APSW code supports Python 2.3 onwards.

SQLite APIs support both UTF-8 and UTF-16.  Py_UNICODE_SIZE is used to select between two code paths - if 2 then the UTF-16 APIs are used and if 4 then a UTF-8 conversion is made and those APIs used.  Python 3.3 makes Py_UNICODE_SIZE meaningless and will be quite a bit of work to integrate as a third branch.

It should be noted that at no point is there any dependence of the underlying bytes/pointer living a long time.  They are only used at the point which data needs to be transferred between Python types and SQLite APIs (both ways) and not held outside of that period.