original question : war of 7 years
I tried to post a rather long answer concerning the spanish succession war, however, it seems to have been lost due to connection problems. I may retype it if I find the will. Meanwhile, let's hope this gets through.
Concerning the 7 years war, there were really three theaters, Europe, America and India.
I must admit I don't know much about the India theater, so I don't know if there is anyway for the french and their indian allies to win. Maybe if Clive is beaten and killed at Plassey, but I don't know if that is likely, and given the RN dominance of the sea, it may just postpone the inevitable.
Concerning the American theater, the battle on the plains of Abraham could easily have switched the other way. This was so balanced, that any butterfly will justify it.
Concerning Europe, if the Death of Catherine is delayed by a few month, Prussia will cease to exist and be dismembered.
If the first happen, the french are likely to keep Quebec ( and just Quebec ). I'm not sure if that impacts the American revolution or not; It may mean that it is cancelled or postponed, or the french presence may be small enough that it gets ignored. If the former, then there are impacts on the french revolution as well, and all is up for grabs, as Napoleon's rise to power is likely stymied.
If the second happens, there are also impacts on the french revolution, as no prussian army may mean no Valmy ... and definitely no Waterloo ( in fact, the Napoleonic wars are nothing like OTL ). Also no German unification by Prussia ( obviously ).
The impacts in Y2k are very difficult to judge. Basically anything which plays with the french revolution and the formation of Germany triggers HUGE butterflies