Equivalence stickiness

If a key owner creates an equivalence binding and then removes it at a later date, should their correspondents who relied upon equivalence to validate the replacement then stop using the replacement, or is the migration from original to replacement sticky?

This can happen in several ways, e.g.

• Alice's equivalent-certificate set "A->B" is updated to "(A,B)->C", but Bob has a stale copy of A. Should Bob consider A equivalent to C or not?
• Alice has "A->B" and Bob uses his trust value for A to derive a trust value for B. Alice then hard-revokes A. Should Bob keep using B?