uhm.
With Fritz out of the way, AugustWhilelm becomes heir to the throne.
He is younger, and we could probably postulate Whilelm dying earlier out of guilt, sadness and alchol.
Thus I would say that Sophia Dorothea has a much greater influence on the young AugustWhilelm boy-king, and she will probably do her utmost to align Prussia to England.
The double-marriage project attempted OTL (Fritz-English Princess Wilhelmina-PrinceofWales) could be proposed ITTL substituting Fritz with AugustWhilelm.
London would probably rebuf it, but Sophia Dorothea being more prone to compromise that her husband, she would probably settle for some lesser english princess.
Thus I'd say we would have Prussia drifting away from the Emperor sphere of influence and towards England.
Austrian succession war is going to happen anyway when Charles VI die, but without Prussia, maria Theresa wins no problem (and keeps Silesia).
Does 7-years war involve it? probably not.
in any case AugustWhilelm at this point die of brain tumor and the (will-be-)Fat King sits on the throne (another boy-king: prussia yill become the laughing stock of europe).
Prussia is, however, somewhat involved in the first poland partition (just the corridor to link OstPreussen to brandenbourg).
In any case, germany is firmly Vienna-centered.
And Napoleon's effect is going to be BIG, much more than OTL