In Denmark the Prussian senior commanders still aren't fully won over to the new system, but I don't see a war with Austria as doing anything other than confirming Prussian tactics. The heavy losses will be on the Austrian side, but without suicidal bayonet charges they will be lower (e.g. instead of 5,719 to 1,112 at Nachod they might get away with 3,000).I was more thinking: if the Austrian tactics leave the Prussians with heavy losses (but still a victory) will the Prussians reform their infantry tactics in response, and will their reforms be good ideas when it comes time to fight the French?
In 1870, the Prussians went into the war expecting to be able to use their infantry as they had in 1866: the first unit into battle engages the enemy, and subsequent waves move to left and right to feel for the enemy flank. That causes them heavy casualties, but - and this is the reason the Prussians keep winning- they're able to change tactics mid-way through the war to leverage their artillery superiority instead. The only real tactical difference as a result of the Austrian experience is that the Prussians might be a little less overconfident.