We had a discussion about this about two weeks ago, where I (and a few others IIRC) expressed the view that Henry V living longer doesn't necessarily win the war for England - I personally have it chalked down to descending into something of a stalemate. I'm reading a lot of books about this era atm, I've even got a TL in mind but in all probability I will never post it as I'm too critical of my own work, but that's essentially the direction my TL goes.
Anyway, as others have also pointed out in different threads, history shows that in basically every single case, the son of a great ruler is invariably a weak ruler or at least a ruler who is strong at different things. Either the son tries to emulate his father and fails (often by taking reckless steps in an attempt to live up to his father's achievements, sometimes fatally), or he is so intimidated by his father's reputation that he simply withdraws from the court circles his father walks in - becoming a scholarly ruler if his father is a military genius, or becoming a hedonistic layabout if his father is known for prudent money control. In this case, Henry VI probably develops somewhat as he does IOTL - refusing to involve himself in the military, utterly committed to peace, and choosing to set a reputation as a studiously religious and temperate man, the perfectly Godly King.