The Feast of the Chair of S Peter was, this year, superseded and obliterated, according to the modern rubrics, by Mass and Office of last Sunday. Yet the Holy Father alluded to it in his address. Laurence Hemming's book Worship as a Revelation suggested that the modern fashion of permitting on each day one unitary celebration (instead of commemorations, Vespers a capitulo .... etc.) is an impoverishment in both diachronic and synchronic terms.
Perhaps the Sovereign Pontiff agrees with that.