I assume that you have read the basic commentaries all of which call
attention to the meaning of binding and loosing among the Rabbis in late
Judaism.
The future perfect periphrastic can be translated "will have been loosed"
(as in ASV margin). It may also be translated "will be loosed" as in a
situation of having been loosed. Perfective action has to be translated in
context and can emphasize either the completed action (close to the aorist,
x happened) or the existing result. GEGRAPTAI = it is written or it has
been written. The big question that bugs those of us who are protestant is
what does this say about Peter? That one could take us far afield.
Carlton L. Winbery
Fogleman Professor of Religion
Louisiana College