What are the potential butterflies?
Well, if John is King, instead of being "merely" acting as Regent until the actual king comes of age, his marital alliance to Burgundy
might be more important, even if his marriage to Anne still proves fruitless; OTL, the crucial alliance with Phillip the Good began to fray after her death in 1432, when John sought out another wife, though I'm not sure what his alternatives are. Alternatively, it is possible if Bedford is King instead of Regent, that
might have effects on his marriage, making it fruitful and cementing the alliance.
Maybe, since Humphrey is the heir to throne after 1422, he marries someone other the Countess of Hainaut. And if both John and Humphrey remain childless as OTL - which is far from guaranteed, mind you - that
could bring in interesting possibilities like Rupert of the Palantine or Eric of Pomerania... or possibly not. Point is, there's a lot of possibilities here.