Erik Moeller wrote in effect:
>However, please keep in mind the one-way
incompatibility that would result
>from adopting a non-copyleft license
A CC-by project could become a CC-by-sa project any time that it wished.
If the incompatibilities between CC-by-sa and GNU FDL are worked out,
then it could become a GNU FDL project.
This is not to say that any such change would go smoothly,
because there would doubtless be resistance from some users
to any change. ^_^