Evidence suggests the two were as fond as two people of different religous views could be. Mary is 24 at the time, not 34. The perfect age for children.

oh yer, maths wasn't my strongest point. So at 24, she is at an even better age to have a child.
Phil still dies in 1541, meaning the marriage is short but happy.
In OTL, Philip died on 4th July 1548, so if they marry in 1539/40 that is still 8-9 years of happy marriage and gives us plenty of room to see Mary get pregnant.
1) Perhaps Mary is a mother of a legit kid who will be 17ish in 1558. Since she is a single mother and perhaps away out Henry (and Edward's) grasp the kid could be Protestant or Catholic depending on how much power Mary has over her kids upbringing (circumstances could vary greatly). Boy would be named Phillip or Edward, girl Katherine or Jane (after Jane Seymour).
Philip, Duke of Palatinate-Neuburg (B. 1503-D. 1548) m. Lady Mary Tudor of England (B. 1516)
1) Philip II, Elector of Palatine and Saxony and Duke of Palatinate-Neuburg (B. 1540) Succeeded his childless uncle, Otto-Henry as Elector Palatine in 1559 at the age of 19, m. Anna of Saxony, the heiress of Maurice, Elector of Saxony
2) Katherine, Duchess of Austria (B. 1541) M. in 1555, John Frederick II, Duke of Saxony (1529-1595)
A nephew of Anne of Cleves.
3) Jane, Duchess of Austria (B. 1544)M. in 1560 to Charles II of Austria (B. 1540–D. 1590).
4) Edward, Duke of Palatinate-Neuburg (B. 1545) M. his cousin Elisabeth of Simmern (B. 1540–D. 1594)
5) Maria, Margravine of Brandenburg-Ansbach(B. 1547) M. George Frederick, Margrave of Brandenburg-Ansbach (B.1539 - 1603)
6) Frederick, Duke of Palatinate-Neuburg (Posthumous birth 1548)