It's been discussed on other threads a Washington win at Brandywine on top of Saratoga likely leads to Britain pulling back North's government falling, & Britain seeking peace and it happening by mid-'79. It appears that even with giving 3 fewer years of money to the rebels, the French Revolution will still occur (from discussion it appears it might have even without the ARW!)
The question is in the 1780s, how much longer does the war continue?]
The US will get the Northwest Territory because troops were sent in Jan, 1778, and that'll be going on while the start of peace is being discussed. But, what about the then-Southwest? Presuming the U.S. does get down to West Florida, does Britain keep West Florida? Or might Spain or even France try to take West Florida? Spain had been making inroads into Florida - taking Mobile in 1780 and further east later. But, would they simply stop once Britain made peace with the US? Or, would the British actually make peace *faster* thinking they had to protect against the French and Spanish?
My thought is the Spanish might take someplace like Baton Rouge but not get any further, and I'm thinking if the French didn't try to take any British colonies OTL, they wouldn't even if the US won by '79.
The funny thing is, I'm looking at the Articles of Confederation and they weren't even approved by every state till Feb. of 1781. It's possible that without the Articles being totally accepted, and John Adams staying around, there might have been some push for an earlier Constitutional Convention.