
Let's get back to basics.  Canon (from the latin) means a rule.  If
we say that a rule is open then its a rule made to be broken.  
There is an issue also of measurement against a rule.  Thus the words
that are spoken need to be compared against the rule/canon but not
added to the canon.

Is new revelation necessary?  Topical, current, personal revelation
I'd say is necessary.  New revelation for all people for all times
is not necessary as we have that in Scripture.

You also seem to confuse canon with scripture.  Scripture may speak of
itself being open - ie God speaking today.  It would speak that it is
closed in the sense that the canon is unchangeable.  (Though the concept
of canon is later historically.)


I agree with the problem of confusion.  If prophecy is meant to encourage,
exhort or correct then is an overlap with scripture.  If prophecy is
meant to bring a `word' of the form "the man you live with is not your
husband" then that is knowledge.  Yet the exact words their are scripture.
I would expect the difference to be the motive and means for delivery.
The reading of scripture itself can be a powerful force.

Regards
 David