Let's say Władysław takes John Hunyadi's advice to stay put and wait until the army is reformed. It does reform after routing the flanks and takes on the Sultan's janissaries. After a while, Murad II sees that he is soon going to be surrounded and flees.
Soon after that, George Kastrioti Skanderbeg manages to join the crusaders.
How much casualties could be caused to the Ottoman forces?
What opportunites does this victory present to the crusaders?
What are the possible pitfalls?
In general, what effects would this victory have?