Probably an important PoD for the Swabian War would be that right before the Battle of Schwaderloh, Count Wolfgang von Fürstenberg was able to stop his troops from raiding the Swiss towns and actually to keep the troops in line and ready for battle.
Since the battle was mostly lost because of the lack of preparation of Swabian pikemen when the Swiss emerged from the nearby woods, had they been prepared, and considering the numeric superiority and the support from several cannons gained from Lucerne's troops , they battle could have been a Swabian victory. And if they had won, they could have advanced south towards Frauenfeld, and after taking over it, they could have easily controlled the entire landgraviate of Thurgau, just as teh Confederacy had done for the last 30-40 years.
I don't have much knowledge of how could the Old Swiss Confederacy react to this, would they surrender after this or would it take to conquer Zurich or another member canton?