IMHO, we have nothing to worry about. Certain permissions were already given in SP, such as having the readings in Masses with the people in the vernacular. I believe this permission was given largely because in some places (e.g., parts of France) having readings in the vernacular only was common practice decades before VII. Currently, having readings in English only seems to meet with a lot of resistance, so, I doubt if you will see it commonly any time in the near future.
I seriously doubt that permission will be given to use the readings from the Missal of Paul VI, and even if permission were given, the option would be seldom used. First of all, the unity of the 1962 Missal and its calendar would be compromised. What would be done during the Season of Septuagessima? And what would be gained? Remember, the primary purpose of the Sunday homily, as JPII reminded us, is catechesis. The Mass is not a meant to provide us with tour of Scripture, which can be achieved more appropriately through other means. As a priest ordained six years, I have preached through the three year cycle twice. Some weeks, you are merely reading a different synoptic account of the same event, and usually the most appropriate one for catechesis is given in the cycle in use in 1962 (e.g., the temptation of Christ in the desert, or the Transfiguration). At other times in the three year cycle, you are often given very similar readings several Sundays in a row (e.g., the Easter season). And at other times, you are given readings that are difficult to preach on, and which many priests mess up terribly (I have heard several homilies about how the gentile woman who begged Jesus to heal her son taught him that his ministry was to more that the Jews alone! Can you think of a greater insult to our Lord? I guess He didn’t understand his mission, or who He is, or that He had to suffer and die… I am sick to death of such heresy!) The readings in the one year cycle of the TLM have the advantage that homilies of the great Fathers and Doctors of the Church are already available for quick reference (so you don’t have to reinvent the wheel), and it seems much easier to review the essentials of the faith each year with the one year cycle.
The addition of propers for new saints is always welcome, and has continued throughout the history of the TLM. If we stopped adding saints for all time with St. Anthony Mary Claret (~1961), then the TLM would be a dead liturgy. The addition of new saints means it is a living Missal in the Church today.
God bless,
Fr. Boyd