Remember the disctinction between Rite and Use. The Sarum was a Use of the Roman Rite. The regular Roman Rite currently has two forms: Ordinary Form (Novus Ordo) and Extraordinary Form (The Tridentine Mass, 1962 edition). But there is, today, also an Anglican Use of the Roman Rite, and that too is capable of having more than one form.
The suggestion that the English Missal is itself a violation of the hermeneutic of continuity,because it is in rare usage these days, seems to be based on the fact that it is not exactly the 1962 Missal in English. But remember it is a bit older than the 1962 edition and that is why I argued that, "the English Missal is the best choice to base an Anglican Use traditional liturgy upon." The main difference between the use of the English Missal as the primary foundation, rather than the Sarum, is that it's purpose was to bring Anglicans closer in line with the current Roman Rite at that time (as opposed to five hundred years ago), of which Anglicans in their Prayer Book already had a Use. As Fr Hunwick wrote, "The authorisation also of the English Missal would in fact make available the Tridentine Rite in elegant, sacral English." The difference between the English Missal and the Sarum Use is that the English Missal (while the particular edition needs to be updated) is, in essence, in litugical/theological continuity with what immediately came before and was currently in use at the present time it came out; the Sarum Use, on the other hand, ceased. Those who say the Sarum can (or should) be resurrected because it was never abrogated have to answer for the fact that the two Sees of York and Canterbury which used it left the Catholic Church, and haven't returned yet. And while they left, they changed the Sarum Use into the Anglican Use (which is not the Sarum, though borrows elements from it). The idea would be to update the English Missal (whether it's called this or something else is no matter) to be in line with the 1962 Missal and its Calendar. A commenter, Osbert Parsley wrote,
I think particularly of the beautiful Sarum plainchant tunes for certain hymns ("Te lucis ante terminum" and "Urbs Hierusalem beata", for example) which are quite different from the modern Solesmes melodies. This music clearly belongs to the "Anglican patrimony". Similar cases could be made for many other aspects of Sarum practice which might be considered for inclusion in the eventual liturgy of the Ordinariate.
This is what could be done either in the updated edition of the new Ordinariate English Missal (or whatever it's called) either in the missal itself or in companion books.
The concern I have is about different Uses in one jurisdiction, as opposed to different forms of one Use in that one jurisdiction. For instance, it matters not whether the Book of Divine Worship is kept and updated or scrapped (and if people want to use a modern form in English they may use the Third Edition of the Novus Ordo), as long as a new tradtional form of the Anglican Use is available. Because it's the same Use. While a modern form (Book of Divine Worship) and traditional form (English Missal) would be two forms of the same updated and reconciled Anglican Use of the Roman Rite (unlike the older Books of Common Prayer created in schism), to include the Sarum Use in the Ordinariate would be to include a separate and different Use than the Anglican one.