WI: Empress Elizabeth had died later?

[Venice]

In the Seven Years' War, the main combatants were:

France
Austria
Russia
Sweden
Spain
Saxony
Sardinia

vs.

Prussia
Great Britain
Portugal
Hanover
Bruinswick-Wolfenbuttel
Hesse-Kessel
Iroqouis Confederacy

The war at that time was dire for Prussia, as it was speculated that his safety was not secure. The British threatened to withdraw support, and the Russians had taken the last Prussian Baltic portn. The Prussians faced invasion from fourt sides: from the West, France was storming the Rhine, from the North, Sweden was capturing Pommerania, from the south, the Austrians were continuing to ivade Silesia, and from the East, the Russians were sweeping through Prussia proper.

Had Empress Elizabeth not died and her Prussophile son not come to power, what could have happened to Prussia? If it collapsed, how could this affect the rest of Europe? Great Britain? The colonies in America?

[Elrodian]

Well first off it was not her son, it was her nephew by her sister Anna. If she stayed alive longer, she would have seen Frederick reduce to a Prince-Elector and East Prussia would have gone to Russia because by the time of her death, Russia had most of Frederick territory, including Berlin. So when she did die, Peter III might stay in power longer because people would not turn on him so fast because he doesn't made peaces with Frederick (which in the OTL real angered the Russian army). What would this mean for Europe? Well the HRE would at lest not be united under Prussia. Also Austria and Russian really have no powerful buffer states to stop them form getting into conflict with each other (with no Prussia they real only have the Turks, this is assuming they divided up Poland when Catherine comes in (which, lets face it, will happen sooner or later)), also if the British are wise, they pull out before Frederick is taken prisoner, because they will most likely lose there Hanoverian possession. If Britain does make peaces, France will remain a colonial power in the Americas