I imagine he would be called Charles ITTL, if he is still born (and as a male)
So the succession of the consrote kings would be like this:
King Consort Henry IX (1518 - 1522) (Henry Brandon, Earl of Lincoln)
King Consort James I (1528-1535) (James V of Scotland)
King Consort John II (1536-1537) (Hans, Prince of Denmark)
King Consort Edward VI (1538-1545) (Duarte, Duke of Guimarães)
King Consort Charles I (1547-1558) (Charles V, Holy Roman Empress)
King Consort Henry X (1560-1572) (Henry Brandon)
King Consort Thomas I (1574-1588) (Thomas Howard