I don't think you can just assume OTL ARW except a couple/few colonies don't join. It would change the complexion of the rebellion and results.
Perhaps, with a larger British bloc of colonies, Spain decides not to openly oppose Britain. At minimum, this means no Florida(s) revanche. At max, this alone threatens the success of the rebellion.
With a solid southern base, Britain can much easier strike at the middle.
But, accepting it at face value, and Spain/France join as OTL, and we end up with an independent USA minus Georgia/South Carolina/North Carolina (and more? Tennessee remains part of NC). Spain might get West Florida through conquest, but it didn't conquer East Florida, so that remains British.
West Florida/New Orleans are going to be easy targets should Spain and Britain oppose each other in war, as they ended up doing in the Nap Wars. Britain absolutely will not let the French back on the continent. However, New Spain is pushing the limit. Britain might foster a rebellion there, but too much resource drain to directly invade.
USA politics change, with the ATL balance of regional power shifting. Continental politics change with the ATL redrawing the map.
I don't know enough about British abolition to comment.