On the OP I think even a unified BNA wouldn't end up being 'the driving force'/ I don't see the capitol moving from London to Philadelphia. The British establishment would not support a move and I would contend that many in BNA would prefer having distance from the capitol/metropole since the metropole often attempts to reign in certain actions by the colonies.
With how the discussion has evolved over if a unified big colony would emerge, if I may invoke how Australia became a federation. That was driven by support within the respective colonies though often overlooked now is that it was an open question if Western Australia would join even when it was culturally not distinctive from the other states. I think in a TL in a POD between say the Glorious Revolution and the ARW I do think that certain differences would result in some colonies becoming seperate states. Quebec is a stand out as without the pressure of the US causing OTL Canada to from I think it is likely that it would probably choose to become independent ITTL.
Another standout is the 'southern'/ Slave states/colonies. While there are going to be butterflies such as them not feeling the need to try to create more slave states to match the number of free states I think it is fair to speculate they may revolt when Britain does outlaw slavery ITTL and thus there would presumably be bad blood between them and the other colonies. The other colonies probably wouldn't want to unite with 'traitors' to from a unified nation and the salve colonies probably wouldn't want the oversight of non slave states since they would like the confederacy of OTL probably try to maintain as much of the pre war setup as possible. Though there could be an open question over if they are kept under extended military rule by Britain in their version of reconstruction.
Now over which colonies would merge, I could IMO see much of the NE US plus NY becoming one state. I could also see this state extending west perhaps even to Oregon. I think within OTL Canada Ontario westward may well join with this state. I think the southern extent of this state would be an open question. Since the salve colonies wouldn't feel the pressure to create other slave colonies I think there will be an open question f how many additional slave colonies/state would there be TTL.
With how the discussion has evolved over if a unified big colony would emerge, if I may invoke how Australia became a federation. That was driven by support within the respective colonies though often overlooked now is that it was an open question if Western Australia would join even when it was culturally not distinctive from the other states. I think in a TL in a POD between say the Glorious Revolution and the ARW I do think that certain differences would result in some colonies becoming seperate states. Quebec is a stand out as without the pressure of the US causing OTL Canada to from I think it is likely that it would probably choose to become independent ITTL.
Another standout is the 'southern'/ Slave states/colonies. While there are going to be butterflies such as them not feeling the need to try to create more slave states to match the number of free states I think it is fair to speculate they may revolt when Britain does outlaw slavery ITTL and thus there would presumably be bad blood between them and the other colonies. The other colonies probably wouldn't want to unite with 'traitors' to from a unified nation and the salve colonies probably wouldn't want the oversight of non slave states since they would like the confederacy of OTL probably try to maintain as much of the pre war setup as possible. Though there could be an open question over if they are kept under extended military rule by Britain in their version of reconstruction.
Now over which colonies would merge, I could IMO see much of the NE US plus NY becoming one state. I could also see this state extending west perhaps even to Oregon. I think within OTL Canada Ontario westward may well join with this state. I think the southern extent of this state would be an open question. Since the salve colonies wouldn't feel the pressure to create other slave colonies I think there will be an open question f how many additional slave colonies/state would there be TTL.