Francois II was a very sickly person, from what I've read. But his marriage to Mary Queen of Scots does open up an interesting set of circumstances. So let's say when "Francois" is born, the child is healthier. French intervention to the rough wooing still results in Mary's engagement to Francois, and the two are as close as they apparently were IOTL. Francois reigns as King of France for a few more years than he did IOTL. And at some point in this extended reign, Queen Mary bears Francois a male child. How does this effect the history of England, Scotland, and France? Who might inherit the English throne post Elizabeth if Mary's immediate heir is the King of France? How does the presence of a young dauphin effect French history? I admit, the scenario I'm imagining is a bit out there, and maybe it's wildly implausible. Still, I'm sure the implications of this are going to be quiet broad in an international sense.
I apologize if the idea is essentially ASB.