There have been quite a few interesting comments on the last post concerning the possible invalidity of consecrations when the consecrator cannot see the elements to be consecrated.
I haven't looked this up (not having much leisure at the moment) but there are a couple of further observations.
Some have remarked that the presence of the elements on the corporal is important. I think that the answer here is both yes and no. Priests are encouraged to make a general intention when saying Mass to consecrate whatever is on the corporal, but it is the intention that matters, not the corporal. That general intention is made in order to guard against an absent-minded moment during the words of consecration. However, the question of intention leads to the second point:
There has to be an intention to consecrate. Once (before the Council) Archbishop (then Bishop) Cyril Cowderoy, celebrating High Mass at the seminary, was alerted to the fact that, at Communion, the ciborium containing hosts for that Mass was still sitting on the credence, having been forgotten at the offertory. He said clearly 'I intended to consecrate enough hosts fot the Mass, therefore they are consecrated', and proceeded to distribute these hosts as Holy Communion.
That this event has been remembered means that even at the time his judgment was considered questionable but possibly correct.
If the Holy Father intends to consecrate all those hosts held in ciboria, then perhaps they are consecrated. But it seems to me that this is open to all sorts of abuse; to reduce it ad absurdum, a sick person could reserve 'blank' hosts at home, the priest making an intention to consecrate one with the morning Mass and, hey presto, it's done; the sick person's daughter, an extraordinary minister, simply gives Communion. Now, that's a very extreme version, but is it really different in kind from the Holy Father consecrating a host at an altar on the steps of St Peter's when the deacon carrying it is still inside the basilica on his way out?