Our second "Summorum Note" was on what changes the motu proprio Summorum Pontificum made to the Law of the Latin Church and the liturgical rights or prerogatives of priests and faithful.
Six years later, are those rights and prerogatives under threat? They should not be, as you can see in Fr. Cassian Folsom's excellent talk on Summorum Pontificum and Liturgical Law, given on Dec. 13 at the Brompton Oratory (we announced the event here):
Despite the practical difficulties involved in this arrangement [two forms in one Rite as established in Summorum Pontificum], Gamber thought that in the long run, it would foster the unity of the Church’s liturgical prayer. “If we allow the traditional rite to continue unchanged and nurture it, alongside the new rite but allowing the traditional rite to exist as a living liturgy, not as a museum piece, it will manifest itself within the universe of the Church and among the different peoples as an important element: the unity of cult.”
Source: PDF document. In audio here at the website of the Monks of Norcia (Nursia).