Even with a son born by Catherine, Henry will want to make sure the Tudor line continues, so his oldest son, Henry, Prince of Wales and Cornwall will be his heir, while future children will be spares.
Henry VIII (b.1491 - 1547) M. Catherine of Aragon [a] (b. 1485 d. 1511) Eleanor of Austria (b. 1498- d. 1558)
1a - Henry, Prince of Wales and Cornwall (b. 1511-)
2b - Edward, Duke of York (b. 1515-)
3b - John, Duke of Kent (b. 1520)
4b - Mary (B. 1521 - )