John Fredrick Parker
Donor
What if Frederick V failed to escape Prague after White Mountain (in 1620)? Or what if he died sometime in 1622, after the Palatine fell? Would this be enough to prevent what would become the Thirty Years War -- the devastation of Germany, the Westphalia system, etc? Put another way:
There is bound to be some sort of conflict or even civil war, but there is no reason why Germany had to face virtual destruction where a third of the population died. Both Britain and France experienced religious conflict, but it never got so bad as in Germany. So "no Thirty Years War" does not mean "no war." Just that any such war lacks the destructive qualities of the historical war.
It's entirely possible that the Habsburgs might have won the war early before Sweden entered the conflict - before Gustavus Adolphus entered, they had practically won after all.
If Frederick V had given up after his defeat at White Mountain, or if he died during the battle, or if Ferdeninad II and he accepted some kind of deal where Frederick abdicated, but his family retained the Palatinate the war stood a very good chance of ending sometime in the 1620s. The war might have lasted only five, eight, or ten years.
The rest of the war would have been averted, and a new constitutional order increasing Habsburg centralized control yet preserving some sort of Protestantism in an increasing Catholic Germany would have become the new status quo.