What if Mary Tudor lived 20 more years?

Mary Tudor does NOT die of anguish at the loss of Calais (or whatever killed her) but drags on a weary existence till, say, 1578, when she dies, aged 65, childless, succeeded by her sister Elizabeth, aged 45, a bitter, frustrated spinster who has had to lie and live alone in country houses all her life.

England becomes thoroughly Roman Catholic (again), as the small Protestant group is increasingly marginalized. Elizabeth has been obliged to become Catholic, but makes a deal that her claim to the throne is not affected by this, her father's will still being the law of the land. She has also declined the hand of the Duke of Savoy, who marries Margaret of Valois instead (as he did in actuality). In fact she continues to hold aloof from the marital sweepstakes, which suits Mary just fine. Mary even beheads the Duke of Norfolk for secretly trying to get Elizabeth to elope with him.

Philip II, however, is without a legitimate heir after the death of Don Carlos in 1568 -- he is unable to marry a subsequent fertile wife until Mary Tudor's death -- by which time he is a gout-ridden 51. Don Carlos, however, has been married to Elisabeth of Valois, and before his complete descent to insanity, has succeeded in fathering a child -- let's say a daughter, Isabel, destined in time to succeed her grandfather as Isabel II of Spain. (She will marry her cousin, Albert of Austria.)

Unsupported by surreptitious Protestant aid from England, the Protestant insurgencies in both Scotland and the Netherlands wither and die. Parma, undistracted by the Armada, takes Den Haag and Amsterdam. John Knox is burned at the stake by order of Mary, Queen of Scots, who marries her first cousin, the widowed Duc de Guise. Mary Tudor, alarmed by all these French forces in Scotland, disinherits Mary and proclaims Lord Darnley the heir to England after Elizabeth, encouraging him to marry Catherine Grey. (They have one son, the future Matthew I.) Willem the Silent is executed in the square of Antwerp. Henri de Bourbon is slain fighting a civil war with the Guises over the throne of Henri III of France. The Duc de Lorraine (husband of Henri II's second daughter) becomes King Charles X. The Armada is sent against Turkey and captures Thessalonika and Rhodes, though not Constantinople (because they can't get past the Dardanelles).

The restoration of a unified Catholicism throughout the West prevents all doctrines of individual human liberty and scientific data from getting very far. North America north and west of Florida is ceded to France. New Paris, at the mouth of the Verrazano River, becomes its metropolis. All the Jews in Europe flee to Turkey. So do the few surviving Protestants.

Discuss.